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THE 



ADULTERATION OF MILK 



HENRY A. MOTT, Jr., E.M., Ph.D. 

MINING ENGINEER AND ANALYTICAL CHEMIST; MEMBER OF THE 

AMERICAN CHEMICAL SOCIETY; MEMBER OF THE NEW 

YORK ACADEMY OF SCIENCES \ FELLOW OF THE 

GEOGRAPHICAL SOCIETY, ETC., ETC. 



NEW YORK: 

TROWS PRINTING & BOOKBINDING CO., 

205-213 East 12th Street. 

1878. 



w- 



THE 



ADULTERATION OF MILK 



HENRY A. MOTT, Jr., E.M., Ph.D. 

MINING ENGINEER AND ANALYTICAL CHEMIST ? MEMBER OP THE 

AMERICAN CHEMICAL SOCIETY; MEMBER OF THE NEW 

YORK ACADEMY OF SCIENCES; FELLOW OF THE 

GEOGRAPHICAL SOCIETY, ETC., ETC. 



NEW YORK: 

TROW'S PRINTING & BOOKBINDING CO., 

205-213 East 12th Street. 

1878. 










r ^ 



Br transfer 
J! 2? "07 



THE ADULTERATION OF MILK. 

BY HENRY A. MOTT, JR., E.M., PH.D. 

This department of the subject of milk is, without 
doubt, the most importaut of all. Surely, every effort 
made to discover or point out the true method for de- 
tecting the adulteration of this most important fluid, 
which is so indispensable to the kitchen, the sick-room, 
and the nursery, cannot help but be received with in- 
terest. For this reason I shall endeavor in this 
paper to consider in detail : 

l s t._The Adulterants of Milk. 

2d.— The Instruments and Methods of Detecting 
Adulteration. 

Before proceeding with the discussion of the first 
division of the subject, it will probably be well to con- 
sider very briefly some of the peculiarities of milk, of 
which undue advantage are taken by milkmen. 

Milk contains two elements, water and fat, both of 
which possess a specific gravity less than that of pure 
milk itself ; these two elements can vary, and do vary, 
between certain limits in pure or normal milk ; but 
when the variations are too great the milk becomes 
abnormal. Between certain limits, then, a sample of 
pure milk may have a low specific gravity, owing to a 
large proportion of water, or it may have a low gravity, 
owing to a large proportion of fat. In the first case the 
milk would be poor and thin, in the latter rich and thick. 
The consistence of two such fluids, a thorough milk- 
man (I mean one posted up to the tricks of his trade) 
could easily distinguish, and it is, I suppose, on the 
business principle, that you should only give a man for 
his money as little as possible, that the milkman, when 
he finds or receives a quantity of milk that is rich and 
thick, partly skims and dilutes it between certain 



4 



limits, knowing that the fraud cannot be detected, 
owino'to the fact that the constituents of milk (especi- 
ally fat) are subject to yariation. I am sorry to have 
to say that this fraud cannot be detected, but it is a 
fact, and we must grin and bear it, for science never 
has nor never ean offer a method for the detection of 
such adulteration. Neither chemical analysis nor the 
various instruments used for detecting adulteration 
can offer any aid. 

Happily, though, for the consumers of this most 
valuable fluid, the limits between which such adultera- 
tion can be carried on are very small, and consequent- 
ly no very serious results could originate from such 
adulteration even to infants. If the milkmen would 
limit their adulteration to this point, we all might be 
thankful, but unfortunately for us they do not conde- 
scend to consult any other source but their pockets. 
Hence there is forced upon the consumers: "Milk di- 
luted largely with water; skimmed milk; skimmed 
milk diluted largely with water, and various decoc- 
tions called milk, containing any number of adulter- 
ants." Fortunately science can interfere with such 
adulterations and frauds as these, and when they are 
detected then a severe and just penalty should be pro- 
nounced upon the perpetrator, who not only robs the 
consumers of their rights, but sends many an infant 
to its grave. 

1. — The Adulterants op Milk. 

The adulterants, said to be used by different writers 
for the adulteration of milk, are quite numerous. Al- 
though water and, sometimes, chalk, soda, and caramel 
are practically the only adulterants that are used, the 
proper treatment of the subject demands the considera- 
tion of all the other adulterants, no matter if the con- 
sideration extends to the brains of the sheep. 

1. Water. — This fluid is the most prevalent adulter- 
ant of milk — it costs nothing, and possessing a speci- 



fie gravity less than that of pure milk, the gravity of 
this fluid may be reduced at pleasure. The amount of 
water added by milkmen ranges between 10 and 50 
per cent Dr. Chandler, 1 from numerous and valuable 
investigations of the milk supply of New York, con- 
cluded that the average milk sold consisted of three- 
quarters milk and one-quarter added water. The 
120,000,000 quarts of milk sent annually to New York 
receive an addition of 40,000,000 quarts of water, 
which, sold at 10 cents per quart, brings $4,000,000 
per annum, or $12,000 per day. 

There are a few persons who are disposed to make 
light of the adulteration of milk by water, but to an 
educated mind they only display their ignorance. The 
addition of water to milk or, worse, to skim milk 
greatly decreases the percentage of the milk solids (as 
proven in the following table), and consequently ren- 
ders the milk not only unfit for the food of infants but 
in many cases dangerous. 

If the water used to adulterate the milk is not pure, 
we have danger arising from another source. There is 
recorded a case 2 where an epidemic of typhoid fever 
occurred near G-lasgow, Scotland, in 1872-8 by the 
milkman adulterating his milk with foul water, and 
allowing his cows to slake thirst from such water. 
Thirty -two out of thirty-nine families which were sup- 
plied with this milk, as also the family of the milk- 
man, were attacked. Families supplied by other milk- 
men were not affected. 

The fever germs were propagated through the adul- 
terating of the milk with this foul water. Another 
case is reported : "In one of the healthiest suburban 
sections of London 500 cases of typhoid fever were 
found distributed in 104 families, 96 of which were 
supplied with milk from one dairy. The contagion 



1 Johnson's Cyc, article Milk. 

2 See Willard's Practical Butter Book, p. 24. » 



6 



Table of the quantities of milk solids contained in 100 
farts of a mixture of water and -pure milk, in differ- 
ent proportions. 1 

BY CESAIRE REYNARD. 



Milk. 


Water. 


Milk solids. 


Milk. 


Water. 


Milk solids. 


100 





12.9200 


64 


36 


8.2688 


99 


1 


12.7908 


63 


37 


8 1396 


98 


2 


12.6616 


62 


38 


8 0104 


97 


3 


12.5324 


61 


39 


7 8812 


96 


4 


12.4032 


60 


40 


7.7520 


95 


5 


12.2740 


59 


41 


7 7308 


94 


6 


12.1448 


58 


42 


7 2016 


93 


7 


12.0156 


57 


43 


7 1724 


92 


8 


11.8864 


56 


44 


7.0432 


91 


9 


11.7572 


55 


45 


6 8140 


90 


10 


11.6280 


54 


46 


6 6848 


89 


11 


11.4988 


53 


47 


6 5556 


88 


12 


11.3696 


52 


48 


6.4264 


87 


13 


11.2404 


51 


49 


6.2972 


86 


14 


11.1112 


50 


50 


6.2600 


85 


15 


10.9020 


49 


51 


6.1308 


84 


16 


10.8528 


48 


52 


6.0016 


83 


17 


10.7236 


47 


53 


5.9724 


82 


18 


10.5944 


46 


54 


5.9432 


81 


19 


10.4652 


45 


55 


5.8140 


80 


20 


10.3360 


44 


56 


5 . 6848 


79 


21 


10.2068 


43 


57 


5.5556 


78 


22 


10.0776 


42 


58 


5.4264 


77 


23 


9.9484 


41 


59 


5.2972 


76 


24 


9.8192 


40 


60 


5.1680 


75 


25 


9.6900 


39 


61 


5.0388 


74 


26 


9.5608 


38 


62 


4 9096 


73 


27 


9.4312 


37 


63 


4.7384 


72 


28 


9.3024 


36 


64 


4.G532 


71 


29 


9.1732 


35 


65 


4 5220 


70 


30 


9.0440 


34 


66 


4.3928 


69 


31 


8.9148 


33 


67 


4.2636 


68 


32 


8.7856 


32 


68 


4.1344 


67 


33 


8.6564 


31 


69 


4.0522 


66 


34 


8.5272 


30 


70 


3.8760 


65 


35 


8.3980 









1 Journal de Chimie Med., p. 358. 1856. 



was traced directly to the water used for washing the 
milk cans and retained in the milk, the water being 
previously polluted by sewer drainage." 

All stagnant water contains organisms either animal 
or vegetable, that renders it unsafe to use, or to allow 
cows to drink. In the case of pure spring water or 
running water, which likewise contains organisms, 
there is not sufficient organic matter in suspension to 
promote their development. In the case of stagnant 
water the organic matter in suspension or in solution 
creates in the water the proper mediums suitable for 
the development of living organisms. "It 1 is no 
longer mere water — it is a world of microscopic ani- 
mals and plants which are born, live, and increase with 
bewildering rapidity. Drink a drop of this water and 
you swallow millions of minute beings." Use this 
water to adulterate milk and you furnish more nourish- 
ment to these little organisms, which continue to mul- 
tiply, and then give the milk to an infant for food 
and you supply with it organisms which are capable 
of producing violent cramping and purging, as also 
capable of setting up putrefaction in the tissues. 

2. Chalk. — This substance is sometimes used to pro- 
duce a thickness and opacity to milk that has been 
diluted with water ; it is also used to neutralize the 
acidity in sour milk. 

3. Starch, Flour, Decoction of Barley, Rice, and 
Emulsion of Almonds and Hempseed are said to be used 
to thicken milk and to neutralize the blue color caused 
by dilution. 

4. Cane Sugar, Dextrine, Milk Sugar, Gum Traga- 
canth, Gum Arabic, and Borax are sometimes used to 
increase the specific gravity of diluted milk and 
sweeten the same. 

5. Salt (sodic chloride) is used to increase the epe- 
cific gravity of diluted milk and to bring out the flavor. 

1 Scientific Conversations by M. Porville. Paris. 



8 



6. Turmeric, Annatto, Caramel, juice of certain roots, 
such as the Carrot or the different flowers, Marigold, 
Saffron, and Safflower, are used to color the fluid so as 
to hide the blue color due to dilution. 

7. Carbonate or Bicarbonate of Soda is used to pre- 
vent the milk from becoming sour, by neutralizing the 
acidity; also to increase the specific gravity of diluted 
milk. 

8. Gelatin and Isinglass have been used to thicken 
diluted milk. 

9. Cerebral matter, Sheep's Brains, Calves' 1 Brains, 
or Horses' 1 Brains, have been detected in milk. They 
were used to thicken the milk after first watering the 
same. 

Having enumerated over the adulterants said to be 
used for the adulteration of milk, I will now proceed 
to the discussion of the second division of the subject, 
namely : 

2. — The Instruments and Methods for Detecting 
Adulteration. 

The first requisite, before proceeding to apply a 
rapid and practical test to the examination of milk, is 
to ascertain the nature of the adulterants used, so as 
to know what has to be coped with in the examina- 
tion. If a given sample of milk, known to be adul- 
terated with several of the adulterants mentioned 
above, is presented to a chemist to discover the nature 
of the adulterants, the only method for arriving at 
the required result is by chemical analysis. Knowing 
the adulterant or adulterants used, then a more rapid 
method may be adopted for their detection. It is well 
though, in large cities, from time to time, to make 
analyses of the adulterated fluid, to ascertain whether 
or no the adulterant or adulterants have been changed ; 
for it might become necessary to change to a cer- 
tain extent the method of examination. Experience 
has demonstrated that water is, in 99 cases out of 



9 

100, the only adulterant used for the adulteration 
of milk. This has been clearly demonstrated in 
this country, in England, Scotland, France, Belgium, 
Germany, and Switzerland. Let us now consider the 
instruments and methods for detecting its presence in 
commercial milk. 

DETECTION OF THE ADULTERANT, WATER. 

The detection of water, when employed as an adul- 
terant of milk, is not always possible, for two reasons : 
1st, because science does not offer any method for 
distinguishing the water naturally present in milk and 
the added water ; 2d, because the percentage of water 
varies so much in pure milk, that it is only possible to 
detect added water when the quantity present exceeds 
the maximum quantity in pure milk. No matter what 
method we adopt to detect adulterated milk, whether 
it be chemical analysis, the lactometer, the microscope, 
or the various other instruments and methods to be 
described, a standard which shall represent the poorest 
pure milk has got to be adopted. When it is desired 
to use the specific gravity of milk as a test for its 
purity, the specific gravity adopted as a standard must 
represent the gravity of the whole pure milk. 

To determine this gravity any number of experi- 
ments have been made : but, before proceeding to the 
consideration of the different experiments, let us glance 
for one moment at the various specific gravities stated 
by prominent writers which are given to represent the 
weight of milk : 

SPECIFIC GRAVITY OF COW'S MILK. 

1.030 to 1.039.... Simon. 1 

1,0302—1.0396 Vernois & Becquerel. 2 

l'.026— 1.032 Scherer. 3 



1 Animal Chem., Eng. ed., p. 50. 

2 Anal. d'Hygiene Publ., Avril, 1857. 

s Physiol., von Dr. Wagner, 1850, p. 450. 

1* 



10 



1.0395-1.0343 J Fleischman.' 

average 1.0317 \ • g 

1.0324 (average) Brisson. 2 

1 -^-}° m A Quevenne.* 

1.0322 (average) \ ^ 

t0 f n trJ- 0357 J Macadam.' 

1.032 (average) ) « 

1.032 (average) \ . . Wiggin. 5 

1 -" 2 »- 1 ; 040 J-- Mott. 

1-032 (average) \ ess 

1.02958—1.0354 ) T „ n , , 

1.03184 (av'ge) [ Je P son & Gardner. 6 

[ 1.02958-1.03538 ) w „ 7 

1.03219 (av'ge) f" vvaiier. 

i 1.029—1.034 (whole milk). . .Hassal. 8 

j 1.026—1.031 Hassal. 9 

1.028—1.032 Wilson. 10 

1.026—1.036 Atcherley. 11 

1.029. . . . , Gorup v. Besanez. 12 

1.030 (lowest) Marchand. 13 

1.029—1.034 C. MiUler. 14 

1.031494 (average) J. Blake White. 15 

1.027—1.033 ) au i i6 

1.030 (average) \ Sharpies. 16 

] 1.026—1.035 Parkes." 

1.026—1.032 Klencke. 18 

S 1.0271 (average) Orthman. 

1.0248—1.0348 Pincus & Struckmann. 

1.02958—1.0348 Chandler. 19 

1 Jahresb. Th. Chem., XIII.-XV. (3), p. 237. 

2 Rees' Ency., 1819, article "Milk." 

3 Diet. Ency. des Sci. Med., p. 130. 

4 Amer. Chem., 1875, May, p. 419. 

6 Report, 1870-71, Providence, R. I. 

6 City Record, July 29, Oct. 7, 1875. 

7 School of Mines, Columbia College. 

8 Adulteration of Pood, new ed., p. 408. 

9 Adulteration of Pood, old ed., p. 216. 

10 Handbook of Hygiene, p. 42. - 

11 Adulteration of Food, p. 61. 

12 Physiol. Chemie, p. 332. 

13 M^ moires d' Agriculture, Paris, 1858, p. 305. 

14 Anleitung zur Prufung der Kuhmilch, p. 47. 

15 City Record, Aug. 17-24, 1676. 

16 Proc. Amer. Acad. Arts & Sci., p. 149 (vii.). 

17 Practical Hygiene, p. 216, London, 1866. 

18 Die Verfalschung der Nahrungsmittel und Getrauke, von 

Herman Klencke, 1S58. 

19 Johnson's Cyc, article "Milk." 



11 



In reviewing the above figures, quite a difference will 
be observed ; but, fortunately, this difference can be 
readily explained. The object of most experimenters 
has been simply to determine the specific gravity of the 
particular samples they have had under examination, 
and their results are correct for those particular sam- 
ples, but incorrect if they are meant to represent the 
specific gravity of all the milk from a milking thor- 
oughly mixed together. 

When I speak of the specific gravity of the milk of 
a cow, I mean the specific gravity of all the milk from 
the cow (in perfect health) thoroughly mixed together, 
obtained at her regular hour of milking, not the spe- 
cific gravity of the first, middle, or last portion, for 
each of these portions give an entirely different specific 
gravity peculiar to themselves. The following are 
tests of the first and second drawn milk from eight 
different cows : 1 



First drawn milk. 


Second drawn milk. 


Cows. 


Specific 
Gravity. 


Cream. 


Cows. 


Specific 
Gravity. 


Cream. 


1.... 

2.... 
3.... 
4.... 
5.... 
6.... 
7.... 
8.... 


1.027 
1.026 
1.027 
1.029 
1.030 
1.030 
1.029 
1.031 


9 
13 

8 

7 

11 

8 

H 

2 


1.... 

2.... 
3.... 

4.,.. 
5.... 

6.... 

7.... 
8.... 


1.023 
1.023 
1.025 
1.024 
1.024 
1.022 
1.026 
1.030 


25 
22 
10 
15 
32 
25 

7i 

5 


Total... 




61| 


Total... 


1 141* 



Schubler found that, on fractioning the milk at a 
milking, the — 



1 London Lancet. 



12 



Specific Gravity. Cream. 

First portion showed 1.0340 5 per cent. 

Second •• " 1-0334 8 " » 

Third " " 1.0327 11.5 " " 

Fourth " " 1-0315 13.5 " " 

Fifth " " 1.0290 17.5 " " 

Average 1.0321 11.0 " " 

Jepson & Gardner, Milk Inspectors for New York, 
found the milk and strippings of two cows : 

Entire Milk. Strippings. 

First cow. . .Specific gravity 1.0348. .1.02610 lact. 90 
Second cow. " " 1.0319. .1.02668 lact. 92 

What, then, is the specific gravity of cow's milk ? 
Or what is the range of the specific gravity ? I have 
already stated that a number of experiments have been 
made to determine this important point, and we will 
now proceed to consider them : 

Dr. Fleischman, 1 of Germany, personally inspected 
the milk of thirteen different dairies in the vicinity of 
Linden, containing in the aggregate one hundred and 
twenty-three cows. He noted the specific gravity of 
the milk of each cow separately and upon each day, 
in bulk, with the following results: 

" The mean specific gravity from the 123 cows is 
1.0316908." " The maximum specific gravity of any 
one of the 123 cows is 1.034300, and the minimum 
specific gravity from any one of the 123 cows is 
1.029500." "The milk of 9 per cent, of the cows 
exceed 1.033 in specific gravity." "The milk of 89 
per cent, of the cows ranged from 1.033 to 1.030 in 
specific gravity, and the milk of 2 per cent, of the 
cows was below 1.030 in specific gravity." "The 
mean specific gravity of the milk from the 13 dairies 
ranged between 1.03065 and 1.03285, or, in round 
numbers, between 1.031 and 1.030." 

Quevenne 2 tested the milk from 103 cows, his ex- 

1 Jahresb. Th. Chem., XIII.-XV. (3), p. 237. 

2 Die. Ency. Sci. Med., p. 130. 



13 



periraents extending over a period of eleven years. 
He found the average specifie gravity 1.0322, and for 
the range 1.0288 to 1.0364. He only found one sample 
of specific gravity 1.0288 ; he found six samples be- 
tween 1.029 and 1.030, five samples above 1.035, and 
ninety-one samples between 1.030 and 1.035. 

Dr. Steven Macadam * made a number of tests at 
three large dairies in the neighborhood of Edinburgh. 
He found the specific gravity to range from 1.0284 to 
1.0357; the average of forty-four trials of different 
milks being 1.03220. The milk was taken direct from 
the udders of the cows. 

He found only one sample of specific gravity 1.0284, 
one of 1.0294, and one of 1.0296. All the other 
samples had a specific gravity between 1.0304 and 
1.0357. 

Jepson & Gardner 2 tested the milk of 109 cows (45 
Harlem and 65 Orange Co., N. Y.) ; they found, for 
the average, the special gravity 1.03184, for the range 
1.02958 and 1.0354. 

Dr. Waller tested the milk of 86 cows and obtained 
the average specfie gravity 1.0321, and for the range 
1.02958-1.0353. 

Dr. J. Blake White 3 tested the milk of 129 cows at 
six dairies, making 142 examinations, and found the 
total average specific gravity 1.031494. 

Lastly, Dr. Christian Miiller 4 had made, under his 
control, " in the newly-erected manufactory of con- 
densed milk of the Swiss Company, Moleson," a large 
number of milk tests. Out of the first 280 weighings 
in the month of March, 1872, only two cases were 
found under 1.030, namely, 1.0286 and 1.0298. Over 

1.033 to and with 1.034 there were twenty cases ; over 

1.034 only two, the highest being 1.0344. Two hun- 



1 Amer. Chem., May, 1875, 419. 

2 City Eecord, July 29, and Oct. 7, 1875. 

3 City Eecord, Aug. 17 and 24, 1876. 

* Anleitung zur Priifung der Kuhmilch, p. 55. 



14 



dred and fifty-seven weighings varied between 1.029 
and 1.033. "As the average of all the tests," he says, 
"I obtain a figure which is only a very little larger 
than 1.031. With respect to the milk which gave the 
specific gravity 1.0286, it came from a spayed cow, 
which was already fattening and gave daily two quarts 
of milk that had, moreover, a bitter taste." 

From the above most elaborate experiments an un- 
prejudiced mind will not hesitate to say that the speci- 
fic gravity of the whole milk from cows in perfect 
health will never fall below 1.029. And if we see 
stated the specific gravity of a cow's milk below 1.029, 
we may be sure that either the milk is abnormal, the 
sample tested not a fair average of all the milk that 
could be obtained from the cow at her regular hour of 
milking, the sample has been tampered with, the in- 
strument used to obtain the specific gravity incorrect, or 
that the temperature at lohich the specific gravity was 
obtained could not have been the conventional temper- 
ature 15.5, O. (60° F.). With respect to the two 
samples recorded, one by Quevenne and the other by 
Macadam, which gave a gravity slightly below 1.029 
within 6 ten thousandths, it is evident that some of 
the above-mentioned conditions were overlooked. 

"No better proof is necessary to my mind than the 
fact that it took the examination of the milk from over 
850 cows to produce two such samples. 

The minute we find a property of milk that is con- 
stant, or, if it varies, does so between certain limits 
that can be definitely fixed, that minute this property 
becomes a standard and test for the purity of milk. 
And it is for this reason that an instrument can be 
constructed, based on the fluctuating gravity of pure 
healthy cow's milk, the indications of which will be 
infallible. 

The original galactometer discovered by Cadet de 
Vaux, in 1817; the Centesimal Galactometers ; the 
Lactodensimeter, discovered by Quevenne, in 1842 ; 



15 



the first instrument called Lactometer, by Mr. Dicas ; l 
the Lactometer, discovered by Edm. Davy, in 1821 ; 
the Milk Tester, discovered by G-reiner, in Berlin, in 
1834; the Milk Weigher of Mollenkopf, Dorssel, and 
G-eissler, in Stuttgart ; and the various other lactome- 
ters are such instruments, which are all hydrometers, 
and differ from each other in the graduation of their 
scales. 

The Centesimal Galactometee, was invented by 
Dinocourt : it is shown in fig. 1. The stem of the in- 
strument has two scales: one for 
pure milk, the other for skim- 
med milk ; the scale A, in part 
colored yelloio, serves to weigh 
the milk with its cream ; the 
first degree on the top of the 
scale is marked 50, which cor- 
responds to the sp. gr. 1.014* 
The following marks extend 
from 50 to 100 (sp. gr. 1.029), 
and over. Each degree starting 
from one hundred in mounting 
up to 50, represents a hundredth 
of pure milk; the degrees 
formed by a line are equal, 
as 50, 52, 54, etc. ; the de- 
grees formed by a dot are un- 
equal, as 81, 83, 85, etc. To 
illustrate by an example : If the 
galactometer is sunk to the 85th 
degree, that will indicate 85 
hundredths of pure milk, and 
consequently that 15 hundredths 
of water has been added to this 
milk ; if sunk to 60 degrees, that 
will indicate 40 hundredths of 



>-_/.03£ 



f.03S 




Fig. 1. 



* Agric. Survey of Lancashire, 1815, p. 550. 



16 



water, or four-tenths of water added. If it is desired 
to count by tenths, it is only necessary to notice that 
the first tenth is white, that the second is colored yel- 
low, the third white, the fourth yellow, and that the 
fifth is also white; towards the middle of each tenth 
the figures 1, 2, 3, 4, 5 are placed to indicate their 
order. 

The scale, a, is in part colored blue, and is destined 
to weigh skim milk ; it is, like the first, divided into 
hundredths (100 degrees), of which the first 50 have 
been cut off as useless, as in the case of the other scale, 
each degree commencing from 100 to 50 and mounting 
upwards represents a hundredth of pure skimmed 
milk, consequently the manner of estimating the quan- 
tity of water added to skim milk is absolutely the 
same as for pure milk with cream. The degree 130 
corresponds to a specific gravity 1.038, the degree 120 
to 1.035, the degree 110 to 1.032, the degree 100, which 
is the standard, to 1.029, the degree 80 to 1.023, the 
degree 70 to 1.020, the degree 60 to 1.017, and the de- 
gree 50 to 1.014. 

Another Centesimal Galactometer 1 was in- 
vented by Chevallier ; it is similar to the above instru- 
ment. It serves to determine the specific gravity of 
cream, milk, and skimmed milk. This instrument is 
used in connection with the *creamometer. The speci- 
fic gravity of the milk not skimmed is first determined, 
noting the temperature, then the volume of cream is 
ascertained by means of the creamometer, and finally 
the specific gravity of the skimmed milk is determined, 
noting the temperature. 

From the data obtained, by referring to tables com- 
piled by Chevallier, the additional water contents of 
the milk is ascertained. 



1 Jour. Pharm. et Chim., 3d series, 1844, t. v. p. 137; Jour. Chem. 
Medic, 4th series, 1856, t. 11, p. 343-401. 



17 



THE LACTODENSIMETER. 

The lactodensimeter J is an instrument differing from 
the galactorneter just described only in the division of 
its scale. It is the production of Bourchardat and 
Quevenne, and is represented in fig. 2. This instru 
ment, like all the densimeters, gives immediately and 
without calculation the density of the liquid in which 
it is plunged ; its scale comprises only the densities 
which may be presented by pure or adulterated milk. 
The shaft bears three distinct graduations. 
The first, which is the middle one in the 
figures, contains the whole numbers inter- 
mediate between 14 and 42. In reality, 
the whole numbers comprised between 
1.014 and 1.042 ought to be inscribed ; but 
on account of the small size of the shaft 
the two first figures have been suppressed 
which do not change. If, consequently, 
the instrument is sunk in a liquid up to the 
figure 29, this signifies that a litre of this 
milk weighs 1.029 grams, and that its den- 
sity is consequently 1.029. The instrument 
has been graduated for the temperature of 
+ 15° C. It is necessary, therefore, for 
obtaining an exact indication, to be assured 
the liquid under examination is at this 
temperature. In the contrary case, it may 
be brought back to this degree by plunging 
the gauge containing the milk in water 
that is cold, or in lukewarm water, accord- 



ing as the thermometer is above or below 
+ 15°. The table given on p. 19 may also 
be employed, which is easily comprehended 
on inspection, and which is extracted from 
the memoir of Bouchardat and Quevenne. 2 




1 See Die. Ency. Sci. Med., p. 144— Lait. 

2 Repertoire de Pharrnacie, juiliet, 1856. 



18 

The scale on the right is employed when it is certain 
that the milk acted on is not skimmed. This scale 
shows what are the variations of the density of milk 
in proportion as water is added, and the figures to, A, 
etc., indicates that the liquid operated upon has been 
mixed with this proportion of water. The scale on 
the left contains the same indications relative to 
skimmed milk. Milk is marked pure on this instru- 
ment between the specific gravities 1.030 and 1.034, 
skimmed milk is marked pure between the gravities 
1.034 and 1.037. 

LACTOMETEK. 

The original instrument that was called a " Lactom- 
eter" was discovered by Mr. Dicas in 1815. The 
following is a description of the instrument by the 
inventor : 

"It is constructed with ten divisions on the stem, 
which is similar to the patent brewing hydrometer, 
and with eight weights, which are to be applied only 
one at a time upon the top, to obtain the weight of 
the milk ; an iron sliding rule accompanies this instru- 
ment, upon the middle or sliding part of which is laid 
down the lactometer weight of the milk, going from 
to 80 ; and opposite thereto are placed the various 
strengths of milk, from water to 160, 100 having pre- 
viously been fixed upon, from a number of experi- 
ments, as the standard of good new milk, and each 
of the other numbers bearing a proportionate reference 
thereto. 

"At one end of the slide-rule, the degrees of heat 
from 40 to 100 are placed with a star opposite as an 
index to fix the slide to the temperature of the milk. 

" The whole being graduated to show the exact 
strength of the milk, as it would appear in tempera- 
ture 55 degrees of heat, although tried in any inferior 
or superior temperature between 40° and 100°; thus 
the great inconvenience which would attend bringing 



19 



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20 



the milk at all times to one temperature is avoided, 
and a simple mechanical method of allowing for the 
contraction and expansion substituted." 

"And as skimmed milk, being divested of the par- 
ticles of butter which existed before skimming, ap- 
pears to have a less degree of affinity with that than 
the new milk has, one side of the ivory sliding-rule is 
adapted to skimmed, and the other to new milk." 

" Genekal Eulb. — First find the temperature of 
the milk with the thermometer, and fix the sliding- 
rule so that the star shall be facing the degree of heat 
the mercury rises or falls to ; then put in the lactome- 
ter and try which of the weights, applied to the top, 
will sink it to some one division on the stem ; add 
the number of the weights upon the top, and that of 
the division together, and opposite to the same formed 
upon the side, will be shown the strength of the 
milk." 

" Examples op New Milk. — If in the temperature 
of 72°, the lactometer with the weight 40 sinks to 9 
upon the stem, fix the slide so that the star shall be 
facing 72° ; then opposite 49 will be found 100°, the 
strength of the milk. Again if in 60° the lactometer 
with 50 on the top sinks to 6 upon the stem, the slide 
being fixed for new milk so that the star shall be at 
60° of heat, then facing 56 will be found 110°, the 
strength of this milk in proportion towards the other, 
provided it is equally replete with cream." 

" To discover which, it becomes requisite these two 
samples should stand a certain time, that the cream 
may rise, which being taken off, they are to be tried 
with the lactometer again, and as the cream is evi- 
dently the lighter part, the milk will appear by its 
denser or better in quality than before. Supposing 
the milk in the first sample to be 57 by the lactometer, 
in 60° of heat, the strength by the skimmed milk side 
of the rule will be 112°- And admit the second sam- 



21 

pie of new milk to be 58, in 64° when skimmed, the 

strength would be 116°. 

"Asa comparison : 

Say Number 1, New Milk 100 

Skimmed Milk 112 

Difference 12 

Number 2, New Milk. HO 

When skimmed 116 

Difference 6 

"From which it appears that Number 1 has pro- 
duced a larger quantity of cream than Number 2, and 
consequently rni^y be deemed the better milk." 

The next instrument receiving the name of lactom- 
eter was invented by Prof. Edmund Davy 1 in 1821. It 
is represented in Fig. 3. It is made of brass, and con- 
sists of a pear-shaped bulb, at the top of which is a 
graduated stem, and at the bottom a brass wire, to the 
end of which a weight is screwed. This instrument 
is only intended for skimmed milk, and the mark 
corresponds to the sp. gr. 1.035, which, according to 
Davy's experiments, represents the lightest genuine 
skimmed milk. The dots in the figures, which extend 
from to 35, indicate parts of water in 100 parts 
skimmed milk at 60°. 

Of the various lactometers that have been in use, 
the only difference was the specific gravity represented 
by the 100 degree of the scale. The specific gravity 
corresponding to the 100 degree on the centesimal 
galactometer invented by Dinocourt, as I have already 
stated, was 1.029, which was intended to represent the 
proper minimum. This sp. gr. has been adopted by 
the Board of Health of New York as the standard for 
their lactometers. 

The old standard adopted by the milk dealer was 
1.030; this was changed by Dr. Chilton to 1.034, and 

3 Triloch's Philosophical Magazine, Nos. 57, 58, p. 241. 



22 



has gradually dropped to 1. 033. So that the standard 
now employed by the milk dealers to secure for them- 
selves pure milk is 0.004 higher than that adopted by 
the Board of Health. 




Fig. 3J 




Fig. 4. 



In graduating the Board of Health lactometer shown 
in Fig. 4, the 100° is placed at the standard 1.029, 



2; 



and at 1.000 ; the gravity of water, the intermediate 
spaces being divided into 100 divisions. Great care 
should be taken to determine with absolute accuracy 
the degree and the 100 degree; other points may 
also be determined, but they are not absolutely neces- 
sary if the space is properly divided. The point to 
which the lactometer sinks in the milk under exam- 
ination indicates the percentage of milk in 100 parts. 
Thus, if the lactometer sinks to 80, the milk must con- 
sist of, at least, 20 per cent, of water and 80 of milk. 
This assumes the original milk to have had a specific 
gravity of 1.029; but, if the milk had originally a 
gravity of 1.034, it would require 16.67 per cent, of 
water to bring it down to 1.029, and 20 per cent, more 
water to lower it to 80° on the lactometer. The tem- 
perature at which examinations are made with the 
lactometer should be 60° F., for exact determinations, 
as the instrument is graduated for that temperature. 
If it is only necessary to establish the fact of an adul- 
teration by water, the milk may be cooled to a tem- 
perature below 60° F., which an expert can easily as- 
certain by the sense of taste, etc. The lower the milk 
is cooled the more dense it becomes ; consequently, if 
the lactometer should sink below 100 in a sample of 
milk known to be below 60° F., sufficient evidence to 
establish the fact of its adulteration is indicated. A 
sample of milk tested by Dr. Chandler, 1 which stood 
at 100 by the lactometer at 60° F., was found to stand 
at 106 at 44° F., at 98 at 66° F., at 90 at 80° F., and 
at 74 at 100° F. 

1 Johnson's Cyclopaedia, article " Milk." j 



24 



Value of the Degrees of the Board of Health Lactometer 
in Specific Gravity. — By Dr. Waller. 



Lactometer. 


Gravity. 


Lactometer. 


Gravity. 





1.00000 


45 


1.01305 


1 


1.00029 


46 


1.01334 


2 


1.00058 


47 


1.01363 


3 


1.00087 


48 


1.01392 


4 


1.00116 


49 


1.01421 


5 


1.00145 


50 


1.01450 


6 


1.00174 


51 


1.01479 


7 


1.00203 


52 


1.01508 


8 


1.00232 


53 


1.01537 


9 


1.00261 


54 


1.01566 


10 


1.00290 


55 


1.01595 


11 


1.00319 


56 


1.01624 


12 


1.00348 


57 


1.01653 


13 


1.00377 


58 


1.01682 


14 


1.00406 


59 


1.01711 


15 


1.00435 


60 


1.01740 


16 


1.00464 


61 


1.01769 


17 


1.00493 


62 


1.01798 


18 


1.00522 


63 


1.01827 


19 


1.00551 


64 


1.01856 


20 


1.00580 


65 


1.01885 


21 


1.00609 


66 


1.01914 


22 


1.00638 


67 


1.01943 


23 


1.00667 


68 


1.01972 


24 


1.00696 


69 


1.02001 


25 


1.00725 


70 


1.02030 


26 


1.00754 


71 


1.02059 


27 


1.00783 


72 


1.02088 


28 


1.00812 


73 


1.02117 


29 


1.00841 


74 


1.02146 


30 


1.00870 


75 


1.02175 


31 


1.00899 


76 


1.02204 


32 


1.00928 


77 


1.02233 


33 


1.00957 


78 


1.02262 


34 


1.00986 


79 


1.02291 


35 


1.01015 


80 


1.02320 


36 


1.01044 


81 


1.02349 


37 


1.01073 


82 


1.02378 


38 


1.01102 


83 


1.02407 


39 


1.01131 


84 


1.02436 


40 


1.01160 


85 


1.02465 


41 


1.01189 


86 


1.02494 


42 


1.01218 


87 


1 .02523 


43 


1.01247 


88 


1.02552 


44 


1.01276 1 


89 J 


1.02581 



25 



Lactometer. 


Gravity. 


Lactometer. 


Gravity. 


90 


1.02610 


106 


1.03074 


91 


1.02639 


107 


1.03103 


92 


1.02668 


108 


1.03132 


93 


1.02697 


109 


1.03161 


94 


1,02726 


110 


1.03190 


95 


1.02755 


111 


1.03219 


96 


1.02784 


112 


1103248 


97 


1.02813 


113 


1.03277 


98 


1.02842 


114 


1.03306 


99 


1.02871 


115 


1.03335 


100 


1.02900 


116 


1.03364 


101 


1.02929 


117 


1.03393 


102 


1.02958 


118 


1.03422 


103 


1 02987 


119 


1.03451 


104 


1.03016 


120 


1.03480 


105 


1.03045 







The following table by Dr. Voelcker, with an addi- 
tion by Dr. Chandler, illustrates the effects of watering 
and skimming: 



- 


UNSKIMMED. 


SKIMMED. 




Sp. G-r. 


Lact. 


Sp. Gr. 


Lact. 




1.0314 


108 


i 1.0337 


117 


10 per cent, water added . . 


1.0295 


102 


f 1.0308 


106 


20 " " " 


1.0257 


88 


I 1.0265 


91 


30 " " «' . 


1.0233 


80 


1.0248 


86 


40 " " " 


1.0190 


66 


j 1.0208 


72 


KQ u u u 


1.0163 


56 


1.0175 


60 



Thus it is seen that with a sample of pure milk of 
sp. gr. 1.0314 more than 10 per cent, of water could 
be added before the gravity is reduced to 1.029 or 100 
on the lactometer; and, after skimming, considerable 
more. 

That the specific gravity 1.029 is the true minimum 
standard for 'pure whole cow's mills, I think I have al- 
ready fully demonstrated ; yet it is interesting to bear 
in mind that it has been confirmed by Muller, 1 Fleisch- 
mann, G-oppelsroder, Kramer, and other specialists?' 1 



1 Anleitung zur Prufung der Kuhmilch, p. 42. 



2 



26 

k 
k Muller 1 says: "From more than 6,000 notes by 
Quevenne and Bouchardat, the minimum is 1.029, and 
the maximum 1.033. For the hospitals and public 
institutions in Paris, the minimum is 1.030." He 
further says: "If" . . . " we go through all Europe, 
from country to country, from place to place, from 
dairy to dairy, from Alp to Alp, with the lactodensi- 
meter in hand, and mix at times the milk of several 
cows together which have been milked under condi- 
tions sufficiently touched upon, we shall find that the 
milk which is divided as a trade commodity from the 
physiological milk weighs between 1.029 and 1.033." 

Let us consider, now, if there are any objections to 
the use of the standard lactometers for the detection 
of adulteration. I have already stated that a sample 
of perfectly pure cow's milk, possessing a high specific 
gravity, can be considerably additioned with water, 
and the lactometer is unable to detect the fraud. The 
question naturally arises, is there any method *by which 
the fraud can be detected ? The answer comes unfor- 
tunately, no — owing to the variation in the proportion 
of each constituent, a proper margin has to be left for 
the maximum and minimum proportions, and between 
these limits the fraud can be perpetrated, and defy all 
Science to detect it. 

Milk may be skimmed, which will increase the speci- 
fic gravity of the fluid ; it may then be watered, and 
the sp. gr. reduced to the standard of the lactometer, 
or the sp. gr. may be still further reduced, and by the 
addition of some solid substance, such as sugar or 
salts, increased to the standard specific gravity. The 
question naturally arises here, can the lactometer de- 
tect such adulteration ? To answer this question, we 
must first inquire into the method adopted where the 
lactometer is used to detect adulteration. It is to be 



1 Correspondenz-Blatt des Niederrheinischen Vereins fur oeffentliche 
Gesundheitspflege. Band vi., p. 82. Dr. Heusner. 



27 



supposed that an expert commissioned to examine 
milk for adulteration, using, as a means, the lactometer, 
will perform the test which is to be made, in connec- 
tion with the senses — that is to say, the sample under 
examination should be examined as to its opaqueness 
and color, its taste and odor, etc. If, on the contrary, 
he performs the test automatically, simply taking the 
degree of the instrument, noting the temperature, 
without examining the sample otherwise — the lacto- 
meter itself will not detect such adulteration ; but 
such an experimenter is not fit or competent to make 
such investigations, for, no matter what the method 
of examination may be, the common sense is always 
required to accomplish the object in view. I say it 
without fear of successful contradiction, that if the lac- 
tometer is used in connection with the senses, that is to 
say, regarding the flow of milk from the bulb of the 
instrument, observing its opacity and color, as also 
examining as to flavor and odor of the sample under ex- 
amination, that the lactometer will detect all the 'prac- 
tical frauds perpetrated oy milkmen. In my opinion 
there is not one unprejudiced person, with the experi- 
ence and education that a milk expert should have, 
that cannot distinguish a fair sample of pure milk 
from a fair sample of skimmed milk or cream ; and, 
if such is the case, how readily could be detected an 
adulterated sample. 

In the first part of this paper I stated that the indi- 
cations of the lactometer are infallible; this is the 
case, for if a sample of milk should indicate a degree 
less than the standard, there is indisputable evidence 
that the sample has been tampered with. 

METHOD OF DETERMINING THE CREAM. 

Sir Joseph Banks was the inventor of an instrument 
by means of which the cream in milk may be deter- 
mined ; this instrument was called by him the Lacto- 



28 



meter, but it afterwards received the more appropriate 
name — Creamometer. It consists of a graduated tube, 
usually eleven inches long and half an inch in diame- 
ter; ten inches of this are graduated in tenths of an 
inch — that is, in hundredths of the whole. To make 
the examination the tube is filled with milk up to the 
100 mark, and set aside for twelve hours; the cream 
rises to the surface, and its volume is determined by 
the thickness of the stratum formed, and which is as- 
certained by noting the number of degrees or tenths 
through which it extends. 

This method is based on the assumption that all 
milk, under the same circumstances, would deposit 
its cream with the same facility, and that the cream 
so deposited would always have the same proportion of 
fat in it. As to all milk depositing its cream with the 
same facility, is evidently a mistake, for experiments 
have demonstrated that the larger the milk globules 
the more rapid will they rise, and the more perfect 
will be the separation of the cream from the milk. 
Valuable investigations by Dr. Sturtevant 1 have shown 
that the milk of a butter-cow consists mostly of large 
globules, whilst the milk of a cheese- cow contains very 
small globules. So that if two samples of milk, one 
from a butter-cow and the other from a cheese-cow, 
were placed in a Creamometer and allowed to rest for 
12 hours, the cream from the butter- cow's milk would 
be far greater than that from the other, owing to the 
fact that the globules rise more rapidly. 

Careful trials of this test, made with different sam- 
ples of milk, whose composition was determined by 
chemical analysis, have shown that it is untrustworthy. 
Baumhauer examined 20 different samples of milk in 
this manner. His results are recorded in the following 
table: 2 



: Ayrshire Cow, p. 239. 

a See Amer. Chem«. Nov., 1876, p. 199. 



29 



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30 



On examining this table we find that experiments 
Nos. 1 and 3 were found by chemical analysis to have 
respectively 2.7 and 3.5 per cent, of fat, while the 
creamometer indicated no difference between them. 
Nos. 5, 10, 15, 18, and 20 were found to contain 3.3, 
3.0, 3.9, 2.3, and 2.7 per cent, of fat, but the thickness 
of the layer of cream formed by all of them was the 
same. 

The addition of water to milk facilitates and hastens 
the separation of its cream, but, of course, does not 

Snu 7W SiTvi 17? Svu Til? "\T\\ i(<f? 




Pig. 5. 



increase the amount, as has been erroneously stated. 
Some creamometers resemble test-tubes in shape, and 
like them, are supported in racks (see Fig. 5) ; they 



31 



are usually graduated only in the upper two inches ; 
others are provided with feet, and are graduated 
throughout their whole length. A great deal has been 
said about combining the indications of the lactometer 
with those of the creamometer — it is very certain that, 
if the indications of the creamometer cannot be relied 
upon, no benefit can be derived by combining them 
with those of the lactometer. 

KROCKEItV APPARATUS. 

Krocker made an apparatus for collecting the quan- 
tity of cream a given sample would furnish, which is 
somewhat of an improvement on the old creamometer. 
The milk is set in shallow vessels, but two or three 
inches deep, from which the cream was afterwards 
transferred to a slender glass cylinder with a gradua- 
ted scale on its side, in which graduated cylinder the 
amount of cream produced by each sample of milk 
could be accurately measured. " In Krocker' s simple 
form of apparatus devised for this purpose (see Fig. 
6) the dishes in which the milk is set for cream to rise 





Fig. 6. Krocker'b Cbeamometer. 

are supported in iron rings attached to an upright 
stand, they taper down to a narrow orifice at the bot- 
tom, closed by a ground glass stopper, the long handle 
of which reaches up through the milk ; on lifting this 



1 Die Milch von Benno Martinez. Also Am. D. Ass. 1871, p. 45. 



32 



stopper, the milk under the cream flows off, and it fs 
easy to mark the precise moment at which the cream 
begins to flow out, when the stopper is put into its 
place and the opening closed till the graduated cylin- 
der can be placed to receive the cream." 

To define the utility of his creamometer, Krocker, in 
1855 and 1856, undertook two series of experiments. 
In the first of them the mid-day milk of 12 different 
cows was put during twenty-four hours at 10 & to 12° 
R., on the one hand, into one or two of his creamometer 
globes 1^ to 2 inches high, on the other hand, into one 
or two cylinders 18 inches high, and the contents of 
the milk of each cow in fat and dry substance were 
determined by Haidlen's method. In the second series 
there were three divisions of experiments each made 
with one sort of milk, the first was to show the dura- 
tion of the skimming in the globes by itself at an 
even temperature, the second the same in comparison 
with the cylinders, and the third the skimming in the 
globes at different temperatures. The per cents of 
cream are ascertained according; to the volume. 



1st Experiment. 



V, 



1 
2 
3 
4 
5 
6 
7 

8 
9 

1U 
11 
12 
13 



Per cent. 


of Cream. 


Per 


cent. 






obtained f 


In the 


In the 


from milk. 


Globes. 


Cylinder. 




Milk, 


A 


B 


A 


B 


Fat. 


Solid 


12.5 


12.25 


11.0 


11,75 


2.30 


12.70 


9.5 


9.3 


6.9 


6.9 


2.50 


11.64 


10.0 


10.3 


8.75 


7.80 


2.73 


12.02 


10.75 10.5 


8.9 


8.4 


2.81 


12.31 


12.50 




12.0 




3.18 


13.24 


11.20 




10.75 




2.75 


13.04 


12.40 





12.0 




3.43 


13.12 


13.25 




13.0 




3.15 


13.20 


10.0 




1S.*0 




2 30 


11.85 


12.4 




8.5 




3,14 


13.13 


12.4 




16. *0 




3.23 


13.20 


10.0 




15.5 




2,63 


12.25 


13.2 








2.63 


12.25 



Eemarks. 



In the original paper for A 
1.40 was given instead of 
12.40 (Ex. 7). 

Milk fresh, acid reaction. 

Very acid reaction. 
Strongly acid reaction. 
Milk No, 12, with 1% of soda 
added. 



33 







2d Experiment 








to 

.2 

"to 


Temper- 
ature. 
Degrees. 
R. 


Vessels. 


Per cent, of cream de- 
posits after standing 
in hours. 


Remarks. 


s 


6 | 12 


18 


24 


40 | 




I 


10 to 12 
10 to 12 

16 to 18 
10 to 12 


Globe No. 1 . . . 
" 2... 

" ■' 3 


19 9! 














11.6 


ii'fl 










" " 4... 








11.9 

14.8 








" '• 5 .. 








With addition of 


II 


Globe No. 1 . . . 
Cylinder No. 1 
Globe No. 2... 


11 2 
10.0 






1% of soda. 


















11.8 

10.5 


12.0 

11.0 








Cylinder No. 2 
Globe No. 3 . . 






























12 6 With beginning 


III 


Cylinder No. 4 






15.2 




11.5 


decomposition. 

Also with decom- 
position. 

With addition of 
1% of soda. 

Indistinct. 


" " 2... 






11.6 


11.5 


' 


Cream layer with 




" « 3 






slightly sharp 
border, 
jMilk already 




4i »; 4 






19, 


thickening and. 
very acid. 








■ 




/ 




■ 



On examining the above tables, it will at once be 
seen that the measurement of the cream even by means 
of the globe is very uncertain as well as of little value 
for ascertaining the fatty contents of milk, although 
its results are much more accurate than those obtained 
where cylinders are employed. The deposit of cream 
of the same milk differed in different globes up to 0.3 
per cent. (Experiment No. 3), in the cylinders up to 
0.75 per cent. (Experiment No. 1) ; the same per cents 
of cream in the globes of different milk, namely, 10 
•percent., came from milk with 2.31, 2.63 and 2.73 
per cent, of fat, (Experiment Nos. 9, 12, 3,) and 12.4 
per cent, of cream from milk with 3.14, 3.23 and 3.43 
per cent, of fat, (Ex. Nos. 10, 11, 7,) while milk with 
nearly the same fatty contents, namely, 3.14, 3.15, 3.18, 
3.23 per cent. (Ex. Nos. 10, 8, 5, 11) furnished in 
2* 



34 



cream in the globes 12.4, 13.25, 12.50, 12.4 per cent., 
in the cylinders 8.5, 13, 12, 16 per cent. 

If experiments 7 and 8 in respect to the globes, and 
10 and 12 in respect to the cylinders, be compared with 
each other, fatty contents of 3.66 per cent, may be 
calculated from 7 for 8, while the same actually 
amounted to only 3.15 per cent., and from 10 for 12 
contents of 5.7 per cent, opposed to 2.63 per cent, 
actual contents (the indistinct separation of cream in 
No. 9 would have given a still greater difference) 
The experiments show further, that the skimming is 
to be considered as ended after 18 hours in the globes 
at 10° to 12° R., while it has lasted as long as 40 hours 
in the cylinders, and that a temperature of over 16° 
R., is less adapted for the determination of the cream 
layer than one of 10° to 12° R. Finally the experi- 
ments show that an addition of 1 per cent., of soda 
to the milk considerably thickened the layer of cream ; 
whether in like measure the separation of fat from the 
milk was promoted is not demonstrated. 

CHEMICAL ANALYSIS. 

Every scientific man will admit that, by chemical 
analysis, the constituents of milk may be estimated 
and the nature of the adulterants in a given sample 
ascertained and determined, provided, the adulterants 
if they are one or more of the constituents of milk, 
the additional quantity exceeds the maximum amount 
present in pure milk. The great objection to chemical 
analysis as a practical means for detecting the adul- 
teration of milk, is that such investigations require the 
practiced hand of a chemist, as also considerable time. 

To practically establish the fact of an adulteration 
(which is all that is wished to be attained oris possible 
to attain) of the numerous samples that have to be 
examined daily in the large cities throughout the 
world, I consider that chemical analysis is perfectly 
useless, for it is very evident that the examination 



35 



must occupy only a few minutes to be at all practical, 
or to admit of a general application. 

That my opinion is not at variance with the opinions 
of those who have the most right to speak on this 
subject, I quote from G-omp Besanez, 1 who says, 
(speaking of the detection of water) : " An exact chem- 
ical analysis of milk would certainly lead most surely 
to the end, but the applicability of this method to the 
sanitary- police control of milk in the larger cities, 
exactly where such control seems most necessary, is 
frustrated by two circumstances : the expense of time 
which every such analysis requires, rendering impossi- 
ble the nearly simultaneous proof of many samples of 
milk, and the fact that such an analysis can only be 
performed by a skillful chemist." 

Christian Muller- says : " Chemical analysis is called 
upon to prove milk and its nature physiologically, to 
characterize morbidly changed milk, and to discover 
the alterations it has suffered ; further, to find out the 
changes which milk undergoes through the influences 
of food, time of day and seasons of the year, of the 
temperature, of the mode of life of the animal, etc. 
Also it furnishes alone the means of proving adultera- 
tions of milk by the addition of such substances as are 
not contained in the normal milk. It cannot, how- 
ever, serve for the detection of adulterated milk, and 
leaves us completely in the lurch when it is wanted to 
confirm the ordinary adulteration of milk, addition of 
water and skimming, in no large measure. If the 
latter adulterations attain such a degree that the 
chemical expert may declare the adulteration by the 
existing scientific notes, there are other means which 
lead to the end far more quickly, with less expense of 

time and money, and with equal certainty 

In accusations of the last mentioned ordinary aduU 



i Physiol. Chemie, Band III., p. 459. 

2 Anleittmg zur Prufung der Kuhmilch, p. 39. 



36 



terations, chemical analysis is of importance to the 
judge only when legally regulated figures are fixed, 
which the chemical expert has simply to seek and 
confirm." 

He also says : l "I have learned with great regret, 
that recently the claims of chemical analysis have 
gained admission into the regulations of a few dairies. 
This is according to my conviction an ever-ending 
series of processes, which will precisely hinder that 
which it is desired to attain, and I consider it a duty 
to earnestly warn against it. Science itself summons 
us, therefore, imperiously before another tribunal, and 
it will be asked : Where do we find this ? The answer 
is easy, and is the lactodensimeter 2 in the dairy." 

Dr. Heusner 3 says : " Chemical analysis has the ad- 
vantage that its conclusions are based on direct proof 
and not on indirect physical methods, but on the other 
hand, according to the statements of Muller, G-oppels- 
roder, and Fleischmann, it is less adapted for the de- 
tection of minor adulterations than Midler's method. 
(Lactometer Method.) The reason of this is, that 
with regard to the percentage of solids and fat there 
are as yet no such reliable and extended observations 
as has been made with regard to the limit of specific 
gravity, and partly owing to the defectiveness of the 
chemical methods thus far employed." 

" Complete analysis is only necessary where foreign 
substances are suspected in milk, and in such cases the 
microscopic investigation should not be omitted." 

The reasoning just given by Dr. Heusner I can fully 
endorse. Surprising as it may seem, out of the thou- 
sands of analyses of cows' milk which have been re- 
ported in the various works, only a few can be select- 
ed, which are fairly stated to represent the analysis of 
an average sample of whole milk. I have frequently 

1 Loc. cit., p. 77. 

2 Lactometer. 

. a Deutscher Verein fur oeffentliche Gresundheitspflege s 1877, p. 51. 



37 



seen stated that the milk examined was believed to be a 
fair average sample of the whole milk, but, of course, 
such statements go for nothing. 

Unless the samples were obtained in the presence of 
the experimenter, or by his assistant in whom he has 
confidence, no great value can be attached to them. 

Any number of analyses representing the whole milk 
from spayed cows or cows being dried off or in other ab- 
normal conditions can be selected, but these would pos- 
sess no value as regards a true standard for pure milk. 

The following analyses given to me by Dr Waller, 
which he carefully made, are of the whole milk, and 
will serve as examples : 



ANALYSIS NO. 1. 

Name of cow — " EecV 

Age — 5 years. 

Peed of cow — Fresh brewer's grain, 

Indian meal, brand with some 

salts. 
Quantity of milk (evening), 3>£qts. 
Whole quantity of milk said to be 

10 qts. per day. Cow in perfect 

health. 
Sample obtained Jan. 15, 1877, in 

the presence of Dr. Waller. 



ANALYSIS NO. 2. 

Name of Cow—" Strawlerry." 

Age— 6 years. 

Feed of cow— Fresh brewer's grain, 

Indian meal, brand with some 

salt. 
Quantity of milk (evening), 5 qts. 
Whole quantity of milk said to be 

10 qts. per day. 
Sample obtained Jan. 15, 1877, in 

the presence of Dr. Waller. 



Lactometer 106°=1.03074 

Cream 12>£# by vol. (16 hours). 
Whey 92° =1.02668 

Average of two Analyses. 

Water 87.202 

Milk solids 12.798 





100.000 




3.389 




4.743 




3.854 




0.812 



Lactometer 103°=1.02987 

Cream by vol. 8.7$ (16 hours). 
Whey 92°=1.02668 

Average of two Analyses. 

Water 87.240 

Milk solids 12.760 

100.000 



12.798 



Fat 3.684 

Milk sugar 4.828 

Casein ^1^ 

Inorganic salts 0.730 



12.760 



The first of the following tables was compiled by 
Dr. Jos. C. Rowland, Assistant Sanitary Inspector of 
K Y. All the milk from each cow, at the time of 
milking, was collected in the presence of Dr. Rowland, 
was thoroughly mixed together by him, a sample cooled 
to 60° F., then tested with the lactometer with the 



38 



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40 



tabulated results. The samples were then given to 
Dr. Waller for analysis, the results being tabulated in 
Table II. 

Although these analyses possess a value, before a 
true standard can be established a large number more 
will be required. 

With respect to the defectiveness of the methods for 
making analyses of milk, no better proof is necessary 
than that most every chemist has a method of his own. 
Gorup. Besanez says: 1 "Strictly speaking only those 
analyses are comparable that are made by the same 
method of analysis." 

As I have already stated, no matter what method 
we adopt to detect adulteration, a standard that will 
represent the poorest pure milk has got to be adopted. 
For this reason the British Society of Public Analysts 
have determined upon the following as the minimum 
proportions of constituents in unadulterated milk : 

Water 88.5 

Milk solids 11.5 

100.0 

Fat 2.5 

Solids not fat 9 



11.5 



The proportion of the fat in this analysis is, in my 
opinion, considerably too low for pure healthy whole 
milk, and it is my opinion, when a large number more 
of analyses are made of the whole milk from cows in 
perfect health, it will be found that the poorest milk 
will have more nearly the following composition : 

1 Physiol. Chemie, Band III., 1875. 



41 



Water 88.0 

Milk solids 12.0 

100.0 

Fat 3.0 

Solids not fat 9.0 

12.0 



If a sample of the whole milk of a cow is found, 
which gives less than 3 per cent, of fat, other samples 
from the same cow should be taken on some other oc- 
casions to verify the result ; if the second and third 
analyses give a greater proportion of fat, sufficient 
proof is furnished, that when the first sample was ob- 
tained the cow was in a slightly abnormal condition. 
When we think how many simple circumstances will 
materially change the composition of the milk of a 
cow, such as even worrying or running the cow, etc., 
we will readily see how necessary it is to make dupli- 
cate analyses as we approach the limits of variation. 

donne's lactoscope. 

An instrument was invented some years ago for de- 
termining the fat contents in milk by M. Donne, of 
Paris. The following observations are by the dis- 



coverer 



i 



"Milk owes its white dense color to the globules or 
fatty matter or butter which it contains ; the more nu- 
merous these globules the more opaque is the milk, 
and the more, at the same time, is it rich in the fatty 
part, or in cream, the more or less opacity being in 
relation with its principal quality — its richness in 
cream ; the measure of this opacity is capable of giving 
them, indirectly, the measure of the richness of the 
fluid, and of indicating its value. 



i See Hassal— Adult, of Foods, p. 227 (1857). 



42 



" But the degree of opacity of milk cannot be ap- 
preciated upon a mass of the fluid ; it is not possible 
to measure it but in very thin layers, and it is this 
which is done with our lactoscope. This instrument 
is constructed in such a way that the milk may be 
examined in it in layers of every thickness, from the 
thinnest, through which all objects may be distin- 
guished, up to that which allows of nothing to be per- 
ceived ; it gives at once the richness of milk, in indi- 
cating the degree of opacity to which the proportion 
of cream stands in relation. 

"The instrument consists of a kind of eye-glass 
composed of two tubes sliding one within the other, 
furnished with two parallel glasses, which approach 
each other up to contact, and separate more or less the 
one from the other at will by means of a very fine 
screw ; a little funnel destined to receive the milk is 
placed at the upper part, on the opposite side is fixed 
a handle, which serves to hold the instrument. The 
tube which screws within the other forms the anterior 
or ocular part, that to which the eye is applied ; it is 
marked with divisions to the number of 50, and figures 
which indicate the richness of the milk. 

" A *few drops of the milk to be examined are 
poured into the funnel. It is necessary to take the 
sample of milk from the mass of the milk, and not 
the surface of the liquid only, where the layers of 
cream collect ; if then the milk has been at rest for 
some time, it must be agitated a little in order to mix 
all the parts. 

" The funnel being full, the ocular tube is turned 
from right to left until the liquid has penetrated be- 
tween the plates of glass, and collected at the bottom ; 
the ocular tube is then turned in the opposite direc- 
tion, from left to right, and one looks through it until 
the flame of a taper or candle can be distinguished. 
At this point stop and impress a slight rotatory move- 
ment, until, by a little manipulation, the light is lost 



43 



to view, without going beyond the moment, when it 
is distinguished, so to speak, and ceases to be perceived ; 
that is the point, definitely, where it is necessary to 
stop ; it is only then required to read the figure of the 
division to which the arrow corresponds : that, we 
suppose, will be 25. The annexed table shows to what 
degree of richness, or to what proportion of cream 
the figure corresponds. 

" The light ought to be placed at about a metre 
(at least three feet) from the observer; a greater dis- 
tance will not impair the accuracy of the operation, 
but it is not the same if one looks from too near. 

" One may assure himself of the accuracy of the in- 
strument by adding a very small quantity of water, or 
even gruel, to the milk. Twenty degrees of water 
are sufficient to change the transparency of the liquid, 
thus milk marking 25, will mark 28 or 30 on mixing 
with it a little water. 

"At the moment when the milk is introduced be- 
tween the two plates of glass, it commonly happens 
that bubbles of air are enclosed in the layer of liquid ; 
it is necessary to drive them out, and this is easily 
done by impressing certain movements on the milk, 
by separating more or less the eye-piece so as to cause 
the two plates of glass to withdraw and approach each 



\J 




Fig. 7. Donne's Lactoscope. 

other alternately. When the trial is terminated, the 
eye -piece is to be removed so as to clean the instrument 
perfectly, and to wipe the glasses ; the glasses ought 



44 



always to be very bright, and one ought to avoid, 
during the observation, to tarnish with the breath the 
glass of the eye-piece." 

Relation of Degrees of the Lactoscope to vol. of Cream 
and Weight of Butter. 



o . 


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J 



Soubeiran, 1 speaking of Donne's lactoscope, says : 
" This instrument is founded on the supposition that 
the opacity of milk is proportional to the quantity of 
fatty matter and casein which it contains ; but it de- 
pends also, probably, upon the diameter of the fatty 
globules, and on the state of more or less perfect sus- 
pension of the casein ; it is therefore attached to vari- 
able natural causes, and consequently the appreciations 
based on the character of the opacity can have no 
precise character." 

DR. HEUSNER 1 S LACTOSCOPE. 

Dr. Heusner 2 has made an alteration in Donne's lac- 
toscope, and says: "In my lactoscope (see Fig. 8) the 
two glass plates are fastened in a short brass ring, and 



1 Nouv. Die., Falsifications et des Alterations, Aliments, etc., Paris, 
1874, p. 309. 

2 Correspondenz-Blatt, etc., Band VI., p. 82. 



45 



one of them is covered with a grating of thick black 
lines (b b'). Between the plates a space remains of 
only 2 millimeters in width (d) that by a cross-piece 
(c) is divided into two halves, one (b') of which is 
destined for the reception of the milk to be examined, 
the other (b) to receive the normal milk used in the 
comparison. 




Fig. 8. Dr. Heusner — Apparatus. 

"To be relieved of the trouble of procuring normal 
cow's milk before each investigation, I have had a 
small plate of milk-glass set into the half (b) of the 
apparatus, which possesses exactly the transparency of 
normal cow's milk in a layer of 2 millimeters thickness. 
The milk to be examined is put in, through a slit- 
shaped opening of the brass case, by simply dipping 
the apparatus into the milk and a cover a- is pushed 
over the slit to close it. After drying, the little instru- 
ment is held up to the bright light and examined to 
see through which half the black lines can be more 
distinctly perceived. If the milk appears more trans- 
parent than the milk-glass, we are justified in inferring 
one of those adulterations by which the fatty contents 
can be diminished. Besides the more simplified 
method of use, this lactoscope has this advantage, 
that it may be used in any light. I will observe that 
the apparatus was ready only a short time before my 
departure, and that consequently I could not find time 
to experiment on its exactness." 



46 



vogel's optical milk test. 

Alfred Vogel's optical milk test is essentially only 
an alteration and simplification of Donng'slactoscope, 
differing from it chiefly in that, instead of measuring 
a milk-layer through which a flame of a candle-light 
is still visible, the quantity of milk is measured that 
is required to render "water so opaque as to cause the 
candle light to disappear completely if looked at 
through a layer of milk of a certain thickness. The 
method depends on the principle that the richer a 
sample of milk is in fat the less of it will be required 
to make a thin layer of water so opaque that a light 
cannot be seen through it. 

" The apparatus 1 required consists of a measuring 
flask, with a mark on the heck, indicating a capacity 
of 100 c.c., a test glass for holding a sample of the 
milk and water between the eye and the light, which 
should have parallel glass sides \ cm. apart so that 
the thickness of the layer of milk looked through will 
be exactly -£ cm., a j)ipette graduated in \ cubic cen- 
timetres, and holding 4-5 c.c, and a box about 16 
cm., long and wide, with a slit in one side, in front 
of which, and 40 cm. distant, the stearin candle is 
placed; the opposide side of this box is so cut out to 
fit the face that when the glass containing the milk is 
put in the box, all light can be excluded while an ob- 
servation is made, except that coming through the 
slit from the caudle; the inside of the box should be 
painted black. 

" To perforin the test, fill the 100 c.c. flask with dis- 
tilled water up to the mark, add to 3 c.c of fhe well- 
stirred sample of the cooled milk, and mix the two 
together thoroughly by vigorous agitation; fill the 
test-glass with this mixture, put it in the dark box, 
and make the observation, placing the eye close to the 
test-glass, and the candle against a dark background. 



1 Agric. Chem., Caldwell, p. 265. 



47 



If the light can be seen, pour the test sample back 
into the flask, add £ c.c. more milk, and make another 
observation ; continue to operate in this manner, add- 
ing ■$ or £ c.c. of milk each time, until the light is no 
longer visible." Add together the different quantities 
of milk, so as to find the total amount which has 
been added, and then ascertain 
from the following table the 
per cent, of butter the milk con- 
tains. The per cent, is calculated 

by the formula 




+0. 



in 



which y == the number of cubic 
Fig. 9. Vo^To^cal centimetres of milk required. 



Test. 



Per cent, of Butter in Milk by VogeVs Optical Milk Test. 



C.c. of 

Milk 
required. 


CD -l-> 

v £ 

P-( O 


C.c. of 

Milk 
required. 


O PS 

nffl 

® u 

?4 o 


C.c. of 

Milk 
required. 


s +> 
a) -a 

Ph o 


1.00 


23.43 


6.75 


3.66 


17.00 


1.60 


1.50 


15.46 


7.00 


3.54 


18.00 


1.52 


2.00 


11.83 


7.25 


3.43 


19.00 


1.45 


2.50 


9.51 


7.50 


3.32 


20.00 


1.39 


2.75 


8.73 


7.75 


3.22 


22.00 


1.28 


3.00 


7.96 


8.00 


3.13 


24.00 


1.19 


3.25 


7 41 


8.25 


3.04 


26.00 


1.12 


3.50 


6.86 


8 50 


2.96 


28.00 


1.06 


3.75 


6.44 


8.75 


2.88 


30.00 


1.00 


4.00 


6.03 


9.00 


2.80 


35.00 


0.89 


4.25 


5.70 


9.25 


2.73 


40.00 


0.81 


4.50 


5.38 


9.50 


2.67 


45.00 


0.74 


4.75 


5.13 


9.75 


2.61 


50.00 


0.69 


5.00 


4.87 


10.00 


2.55 


55.00 


0.64 


5.25 


4.66 


11.00 


2.43 


60.00 


0.61 


5.50 


4.45 


12.00 


2.16 


70.00 


0.56 


5.75 


4.26 


13.00 


2.01 


80.00 


0.52 


6.00 


4.09 


14.00 


1 88 


90. CO 


0.4S 


6.25 


3.94 


15 00 


1.78 


100.00 


0.46 


6.50 


3.80 


16.00 


1.68 







Dr. Lauder Brunton ! says: "Before applying this 
test, it must be ascertained by microscopical examina- 
tion that the milk does not contain starch granules, or 



Physiol. Laboratory, Sanderson, p. 529. 



48 



any other impurity in suspension which might increase 
its opacity." 

This method has been highly recommended for its 
accuracy by good authorities. Kuhn, in his prize 
essay on stock feeding, says that, as he has proved by 
his own experience, "this method enables one in a 
short time, and with but little trouble, to determine 
the fat in a large number of samples of milk with accu- 
racy." 

Caldwell 1 says : " After a little practice the whole 
analysis can be executed in three or four minutes, even 
to the cleaning of the apparatus to have it ready for 
another trial." 

If cream is to be tested, only one cubic centimetre 
is to be added at first and a half c.c. at a time after- 
wards. 

Vogel found that about 6 c.c. of pure cow's milk, or 
3.7 of cream, added to 100 c.c. of water were sufficient 
to form a mixture which quite obscured a candle flame. 
When 8 c.c. are required, the milk contains about 30 
per cent, more water than it ought, either from the 
addition of water, or of creamed milk. When 12 c.c. 
are necessary, the milk contains 50 per cent, too much 
water. 

Hoppe-Seyler 2 alters this process so, that to a mix- 
ture of 5 c.c. of milk and 95 c.c. of water he keeps 
adding water until through a layer of 1 c.c. thickness 
the candle-light becomes visible. 

Dr. Heeren 3 has very carefully examined into the 
merits of the optical test and- says: " The four ex- 
periments performed by me with the most scrupulous 
care were the following : 

"I. Pure milk from quite a fresh milking cow, milked 
in my presence, showed at 14" R., a spec, gravity of 
1.0316. The chemical examination gave fatty con- 

1 Eeport for 1871, Amer. Dairymen's Assoc, p. 50. 

2 Physiol. Chern., Band III., Milch, Gorup Besanez. 

3 Dingler's Polytechnisches Journ., Vol. 193, 1869, p. 403. 



49 



tents at 3.160 per cent. Examined with one of Vo gel's 
galactoscopes, obtained from the mechanician Greiner 
in Munich, 8 cubic centimetres of milk were used, cor- 
responding by the table to 3.14 per cent. The milk 
was divided into two parts; these were kept for 24 
hours in a cellar and the milk of one part was taken 
away from under the cream by means of a siphon. 
This skimmed milk showed at 14° R. 1.0343 spec, 
gravity, and gave 0.701 per cent, by the chemical test; 
by the optical 22 K. C, corresponding to 1.28 percent. 
The second unskimmed portion was now uniformly 
mixed by gently moving about, its specific gravity 
was sought for, which showed itself exactly the same 
as the day before=1.0316, and then by the "addition 
of water it was diluted to a weight 4.508 times as 
much, by which its fatty contents became equal to 
those of the skimmed milk. 

" This diluted milk of 0.701 per cent., fatty con- 
tents showed 0.690 per cent, by the optical test. 

"II. Milk, not milked in my presence, but by the 
statement of the seller asserted to be still intact. . Spe- 
cific gravity = 1.0270. Fatty contents chemically de- 
termined — 5.018; optically 5.61 per cent. Skimmed, 
specific gravity = 1.0312 ; fatty contents chemically 
,1.670; optically 2.8 percent. The unskimmed milk 
reduced by dilution to equal the fatty contents with 
the skimmed gave optically 14 K. C, corresponding 
to 1.88 per cent 

"III. Milk procured from a milkman, probably 
somewhat skimmed. Specific gravity = 1.0265 ; fatty 
contents chemically 4.225 ; optically 5.0. Skimmed, 
specific gra^ity=1.0312; fatty contents chemically 
0.225 ; optically 1.0. The unskimmed portion diluted 
to 0.225 fatty contents, consequently now of equal fatty 
contents with the skimmed, gave optically over 2.00 
K. C. 

"IV, Milk from another milkman, without doubt 
partly skimmed. Specific gravity -= 1.0260. Fatty 
3 



50 



contents chemically 2.312; optically 1.66 per cent. 
The unskimmed milk, reduced by dilution to the fatty 
contents of the skimmed, showed optically 24 K, C. f 
corresponding to 1.19 per cent. 

" A glance at these figures furnishes first of all a 
proof of the actually surprising exactness of the opti- 
cal test, as long as we have to do with whole, intact 
milk, for the diiference between the chemical and 
optical determination in No. I., 3.16 and 3.14, is cer- 
tainly smaller than one might expect, when the grad- 
ual disappearance of the visibility of a candle-flame 
serves as the measure. In No. II. the agreement 5.018 
and 5.61, or 100 : 112, is still less, but the possibility 
is by no means excluded, that the milk, in spite of the 
statement of the seller, may have suffered a slight ad- 
dition of skimmed milk. In Nos. III. and IY., where 
more considerable differences presented themselves 
between the chemical and optical test, 4.225 and 5.0 
(or 100 : 118) and 2.312 and 3.2 (or 100 : 139), proba- 
bly, or indeed without doubt, a partial skimming had 
taken place. 

" In all four investigations the deviations of the 
optical test showed themselves far more strongly in 
the skimmed than in the milk examined before the 
skimming, as the following table shows : 

"Relation of the actual to the optically found fatty 
contents r 

Before Skimming After SMmming^ 

In. No. I. 1:0.997 ' 1:1.82 

" II 1 : 1.12? 1 : 1.7a 

" III 1 : 1.18 1 : 4.44 

"■ IV ... 1 :1.39- 1 1.1..95. 

"By this, the above-made m p)*iori assertion is con- 
firmed, that the optical test will not prove right m 
skimmed milk, because^ owing to the smallness of th@ 

* That is, before the skimming performed by me, without any regards 
a & skimming psrhaps previously performed by the producer.. 



51 



fat-globules, it appears more transparent than it must 
be according to the actual contents. When in these 
experiments the unskimmed milk was diluted by ad- 
dition of water, so far, that it possessed equal fatty 
contents with the skimmed, considerable differences 
were shown optically. There were here, consequently, 
two milks of fully equal fatty contents, which, how- 
ever, were optically different, and must have been so 
naturally, as is shown by the following table : 

Optical test showed. 

Actual contents in the in the 

of both milks. diluted, skimmed. 

No. 1 0.701 0.690 128 

" II 1.67 1.88 2.80 

" HI 0.225 0.268 1.00 

" IV 0.85 1.19 1.66 

"If the milks II., Ill, and IV. had not been already 
partially skimmed by the producer, the figures of the 
second column must have agreed with those of the 
first just as well as in the milk No. I., which was cer- 
tainly not previously skimmed. 

" If we go a step further, the possibility is shown of 
calculating approximately from the combination of 
the chemical with the optical examination, how much 
a milk has been skimmed. Without, however, going 
into this somewhat unfruitful calculation, I will only 
briefly remark that a difference of the optical from 
the chemical examination indicates in any case a 
skimming has taken place, and the greater this differ- 
ence, the more extensive skimming is indicated. Thus 
it results from table A, that the milk No. I. was in- 
tact, next to it the milk No. II. on account of the 
difference, 1 : 1.12, indicates a slight skimming, while 
in III. and IV. the differences, 1:1.18 and 1 : 1.39, show 
that these milks, just as they were received from the 
milkmen, had been already skimmed in a very percep- 
tible degree. 

" Recapitulation. 1 — To facilitate a survey of the 
1 Loc. cit., p. 407. 



52 



somewhat complicated investigations the principal 
points may be again briefly recapitulated : 

"1. Skimmed milk contains smaller fat globules 
than unskimmed milk. 

" 2. Smaller globules cause a greater cloudiness, in 
proportion to the existing quantity of fat, than larger 
ones. 

"3. As the optical milk test is based upon the de- 
gree of untransparency, it can give no serviceable re- 
sults for milk wholly or partially skimmed. 

"4. Careful experiments have confirmed the great 
exactness of the optical test, of the galactoscope of 
Vogel, and of the table calculated by him, but only 
for intact, unskimmed milk. 

" 5. The more the milk has been skimmed, the more 
the optical statement differs from the true fatty con- 
tents. 

" 6. Two portions of the same milk, one by skim- 
ming, the other by dilution brought to exactly equal 
fatty contents, show considerable differences by the 
optical test, and this test gives the fatty contents cor- 
rectly in the diluted milk, but too high in the skimmed. 

" 7. The possibility is given, of ascertaining, by 
combination of the chemical with the optical examina- 
tion, what part of the fat of a milk was withdrawn by 
skimming. 

" 8. The observed increase of the specific gravity of 
the milk by skimming agrees exactly with the increase, 
calculated from the loss of fat, it being supposed that 
the specific gravity of the milk globules is assumed as 
equal to that of the pure butter- fat. If, on the other 
hand, on account of the supposed membranous cover- 
ing, it be assumed as only a little greater, the experi- 
ments do not agree as well. In any case the covering 
must be supposed as of such immeasurable fineness 
that it can scarcely be imagined as existing. 

" However excellent, indeed unsurpassed, the opti- 
cal test, especially Vogel's galactoscope, and, perhaps, 



53 



too, Feser's improvement on it, shows itself for farmers 
and all such persons as can examine the milk in a 
positively unskimmed condition, it cannot be recom- 
mended in the ordinary milk trade, where the milk 
offered for sale is so often, indeed usually, in a partially 
skimmed state, and in such cases I consider conse- 
quently the creamometer always as the most serviceable 
instrument, as the errors of its data do not go so far 
as those noted in the above table A, found by means 
of the optical test, which gave the fatty contents in 
unskimmed milk too high by 1.82, 1.73, 4.44, and 1.95 
times the actually existing." 

M arch and 1 s (de FScamp) Process.— This process 
is based on the determination of the butter by means 
of the lacto-lutyrometer shown in Fig. 10. The instru- 
ment consists of a glass tube closed at 
one end, having an interior diameter of 
0.010 m. to 0.012 m. It is divided into 
three equal parts of 0.10 m., the upper 
part being divided into hundredths. The 
operation is conducted as follows: A 
cubic decimetre of milk is introduced in- 
to the tube so as to be even with the first 
line of the graduation, and a drop of 
potassic hydrate is added to hold the 
casein in solution. Ether is then added 
in equal quantity to that of the milk, and 
the mixture is shaken, when a cubic deci- 
metre of alcohol is added, and the mix- 
ture is again shaken, when the tube is 
put into a water-bath at 40° C, and there 
kept vertical, until the oleaginous layer 
rising to the surface no longer increases ; but as this 
layer contains some ether, and as a small amount of 
butter may still be retained in the lower aqueous fluid, 
a correction of the results is necessary. The following 
table, compiled by Marchand, facilitates this correc- 



-iO 



Fig. 10. 
Maechand's 
Lactobtjty- 

ROMETER. 



54 



^3 



s 

aq 

^ 



s 



k5 



to 

to 

6 




5sa 


<» 






rO 


s 


O 


a 


io 


*, 


*j 


<^ 


<3 


c> 






V 









<5» 



<0 

-si 



»~«i 



Weight 
of the 
Butter. 


bo 




fc~ 2> i> £> i> O £> C- f l> fc- i> fc- t- fc- i> J> 


•saaiSad 




OOOiOrKMCO^lOtDb'OOQOHCiO:^ 




Weight 

of the 

Butter. 


b£ 




OCDOOi>t>t-i>G0000000G0C50i0505 


•saaaSaQ 




OHNCOlHOOi>00050H«W'<j<0!0 








Weight 

of the 

Butter. 


bo 


Tj<!>omNOMi>oeoi>oo:oow© 

NC'iXXlCOflOCOXOJfflOJOOOOOH 


•saaiSaci 


©0S05050J050501OOOOOOOOO 


Weight 

of the 

Butter. 


£ 


rt<£>CSTHTj<X)X)i-HC01O00OC5iO£>05C<l 


OOOOQOC50S05010000i-ItHt-It-(t-h(M 


•saajSaa 




THlOOlX»050HiMCO'^iOOt*QOOiO 


1010lO»OlOlCO«OCOOffl«00©00!> 
rlHHiHrlrlHHTHrlHrlrlHHHrl 




Weight 

of the 

Butter. 


u 

bo 


©QOHM»0000(M^i>©H-*COQOHCO 


aaooooHriHWHNUiiNiMtoco 

CO CO "^ ^ "^ ^ '^ ^ ^* ^ "^ "^ "^t* "*f "^ ^ "^ 


•saaaSaQ 




«Ci>0005OH«C0^1O?0J>0005OH01 


T-trHi-l'i-l«<M<M!MC(i04C5<M<Me«COCOCO 

•HrlHrnHHT-tHnHHTHT-lrii-JrlH 




Weight 

of the 

Butter. 


u 
6XJ 


i>'r-ITtiC-OTj<t>0'<*I>OT^J>OCOi>0 


COCOCOCOCOCOCOCOCOCOCOOOCOCOOtiCOCO 


•saaaSad 




ooaoHWn^iocot-QOQOHCdm-* 


t^i>COOOQOOOOOOOOOG00000050505CSOS 


Weight 

of the 

Butter. 


be 


OD«W050110QO(M1CCOWWQOHWQOH 
OOHCOOOOOCOiOi>OWiff>QrH^ 

O1W03CQC<iC^OiC^Ol7^0J<M(MC5O3C5Cvi 


'saaaSaa; 




OOHOJCJ^lOO^OOOOHCQCO^lO 


CO-^-^^'*'*'*l'*^^'>*i01010iOiCiO 




Weight 

of the 

Butter. 


u 

be 


OCOOOCOOOCO«5 0COOOCOOOiCO 
OG0OC010J>OC<i^J>01i-H^OX)OC0 


«WCOMOTKlTt<'^'*Tt(^iOlOlOUOOO 
HHHHHrlHHHi-lrtHT-lrlrtHH 


•8aaj3aQ[ 




OH«W*IOOi>XlC50HNC0^100 


OOOOOOOOOOTHTHT-(i-trHTHT-( 



00 


















OlOHWOOrHlOOt'COOOHWM^OCD^K OS 
—. ' I '. '. ' ^' ^' _I _J _J h N W W W W W W W N W 






fcj £>' $>' i> t-' t> i> J> J> 00 00 00 CO 00 00 GO GO CO GO OS OS 



ffim©oiWcoffl«fflcs«caNWfflW|OC5W>o 

§»OwSt-05«^OQHMOCOOWiOb;0« 
J J j J j ^' ^ lO lO lO lO ® O S3 00 t- t; t" t- 00 CO 



00 ^ W to t- 00 OS O tH « M ^ lO ffl i> GO OS C H W CO 
CO CO CO* CO CO CO CO* Tt" rH "*' -*' ^ ^ ^' 3* 3 2J S 12 S S 



r«THlffl\o»OlCffitD©CD!>i>f>t-00C000a)C005Q 
COCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOOt) 



JOOt-OOCJSOHffiM^lOfflt-COOJOHWMTlllO 
OS QfflffifflO'o'ddo'oOOOOWHHrjrjH 



)rim 1 -nnQOiHTHflOH'^ , 0O'- l ' , *00HT}t!>'H , *t-H'^ 

§&OHW§ooo«Io?OiO^©C5HMOCoomra 



inin'«Dtofflffli>!>!>i>i>oocooococioffiq®qo 



Ci>00 050H(MX^lOOt'a)05 0H«CO'^ffi!Ot- 

id id id id to cd dddoddddt-£-t-fc-!>J>i>t- 






eocot-t-t-t-t-oooooooooscscsosooooo^T-j 



t-t»0>OH«M^iOCOb-00050H«M-^lCOt-CO 
,_(' ,_| t-I 05 cq> Ci C3 «' <M OT> Ol CNi d CO CO 00 CO CO CO CO CO CO 



56 



tion. (The relation between the weight of the butter 
and degrees of the lacto-butyrometer are in the fol- 
lowing table established according to the formula : 
p = 12 grms. 60 -+- n degrees x 2 grms. 33.) 

According to March-arid a litre of pure milk must 
give from 30.55 gr. to 35.43 gr. of butter. These 
quantities were obtained from 126 analyses made by 
Marchand, and are nearly the same as those found by 
Que venue : 34 grms. for the average, and 30 grms. 
for the minimum. 

Chevallier and Henri give the average 31.3. Mar- 
chand states 1 that he agrees with Quevenne, " that all 
commercial milk, containing less than 30 grms. of 
butter a litre (kilogramme), does not have a normal 
proportion of cream, and that it has experienced a par- 
tial skimming. When the milk is obtained from a sin- 
gle cow, the minimum may be admitted at 27 grms." 

" Milk containing 27 grms. of butter per kilogramme 
marks 6.2° on the lacto-butyrometer, and that contain- 
ing 30 grms. indicates 7.5°. 

"These figures are the smallest that can be admitted, 
and the last (7.5°) has constantly served me as a basis 
in the investigations with which I have been commis- 
sioned. 

"For the authorized inspectors, therefore, the ques- 
tion will always be limited to determine whether the 
milk, which they may have to examine, indicates or 
does not indicate 7.5°. This is an easy verification to 
make ; but when it conducts them to negative results, 
thsy should take care to have the suspected sample ex- 
amined by an expert chemist. This is a measure of 
prudence from which they should never depart." 

Sallbron's Process. — The lacto-butyrometer of Sal- 
leron 2 is shown in Fig. 11. It only differs from that of 

1 Jour, de Pharm. et de Chimie, III. Serie, Tome xxvi. Annee, 
1854, 2a Partee. Page 351. 

2 Nouveau Diet., Des Falsifications et des Alterations des Aliments 
et des Medicaments, par J. Leon Soubeiran, 1874, p. 107. 



h 



57 



- — -Alcohol 



f 



-~\ 



C 5 > 



■JEthef. 



—Milk 



Flo. 11. — Sallebon (Lacto-Butyrometer). 

Marchand in having a graduated index, which gives 
directly the butter-contents of the milk ; the first divi- 
sion of the index indicates, instead of 0, 12.6, and cor- 
responds to 12.6 grms. of butter remaining in solution. 
The instrument has a tin tube for a case, which serves 
as a water-bath, and is supplied with a cup at its base, 
in which the alcohol is burned. 

Lecojsttb's Process. — This process con- 
sists in putting into a graduated tube 
(shown in Fig. 12) five cubic centimetres 
of milk, then twenty cubic centimetres of 
crystallized acetic acid and then closing the 
upper orifice of the tube, and shaking for 
several minutes. The casein that had been 
coagulated is dissolved little by little, and 
the butter floats rapidly on the liquid in 
the form of white flakes. The butter is 
liquefied by means of the flame of an al- 
cohol lamp, and a liquid layer is thus ob- 
tained, whose volume is easily ascertained 
by means of the graduations on the tube. 
The apparatus is composed of a tube of Fig. 12. 
about 0.025 m. in diameter, closed at one appabatus. 




58 

1 
of its extremities, and divided into five parts, each 
presenting a capacity of five cubic centimetres; to 
the upper part of this tube is joined another tube 
of much smaller diameter, and divided into twen- 
tieths of a cubic centimetre ; then, to the upper part of 
this second tube a third tube of the same diameter as 
the first, but much shorter and not divided, serving as 
a funnel, is joined. This last tube receives the liquids 
which are dilated during the operation. 

HOItSELEY'S INSTRUMENT. 

This instrument consists of a tube, which is divided 
so that every degree is one-hundredth of the whole. 
The milk to be tested is poured into the tube until it 
measures 250 grains, opposite which is a mark, A. 
Methylated ether is then added until the next mark, 
B, is reached, and the whole well shaken together for 
five minutes ; methylated spirits is next poured in to 
10° of the graduation, (7, and again shaken for five 
minutes. On placing the tube in the stand the fat 
will rise to the top as a bright yellow oil, the measure 
of which will indicate the weight, because each gradu- 
ation is equal to 4.15 grains of fat. The casein sep- 
arates and falls to the bottom of the tube as a white 
mass, capable of being strained off, dried, and 
weighed. The remaining fluid after evaporation to 
dryness will give the amount of sugar and salts. 

As an example : a rich sample of milk from an Al- 
derney cow gave four graduations of fat from 250 
grains of milk. Therefore, 

4x4x4.15 = (mfat> 



10 

The sediment equalled 10.8 grains ; so that 

10.8 x 4 , 00 

— — 4.32 casein. 

10 



59 



Residue after evaporation, 7 

14.2 x 4 *°=™ 

— = 5.68 salts and sugar. 

Total solid contents = 16.G4 per cent. 

A sample of diluted milk. 

No. 2 gave three gradations for fat, 

— — — - = 4.98 per cent. 

It has had 25 per cent, of water added. 
No. 3 gave one gradation, 

1 x4x4.15 i „„ 

= l.oo per cent. 

10 L 

It has had 50 per cent, of water added, and had 25 
per cent, of fat removed. 
No. 4 gave two gradations, 

2 x 4 x 4.15 Q 00 , 

3.32 per cent. 

10 F 

This had had 50 per cent, of water added. 

W. W. Stoddart, speaking of Horsley's instrument, 
says: J It " shows the fat or cream distinct and per- 
fectly separated. By it you can calculate the weight 
per cent., and estimate the casein, the sugar and salts 
with great ease and rapidity. Indeed, the whole 
operation only takes ten minutes, or the quarter of an 
hour, and the results may be kept for observation for 
any length of time ; an advantage of no mean impor- 
tance when legal consequences are dependent on the 
analytical evidence. 

CHAMELEON TEST. 

E. Monier 2 has founded a peculiar optical process 
for testing milk on the fact that potassjc permanga- 
nate is equally discolored by casein and albumen. A 

1 Pharm. Jour, and Trans., September, 1874, p. 188. 

2 See Die Milch, von Benno Martinez, Vol. I., p. 174 ; or Monier, Nou- 
velle methode pour Tanalyse du lait au moyen de liqueurs titrees, 
Compt. Bend., xlvi., 1858, p. 236. 



60 



two per cent, normal solution of casein is compared 
with the milk to be tested, and the volumes of a solu- 
tion of potassic permanganate are determined, which 
must be added on one hand to the solution of casein, 
on the other to the milk, in order to obtain a lasting 
color of equal intensity in both. As these volumes 
are proportional to the existing quantities of casein and 
albumen, the contents of the milk in the two latter 
may be calculated from them. If the contents of 
casein and albumen are to be separately ascertained, 
the casein is first separated from a second portion of 
milk by means of a little acetic acid under warming to 
40° to 50° C, and the albumen in the remaining liquid 
is determined as before. If the fatty contents of the 
milk are to be ascertained, the previously obtained 
precipitate is dried, and the already known casein con- 
tents are subtracted from it, the remainder giving the 
fatty contents. Experiments are wanting to show the 
utility of this method. 

HALTMETRIC TEST. 

Reichelt, of Ausbach, 1 has applied the halimetric 
test, proposed by Fuchs for the examination of beer, 
to the determination of the aqueous contents of milk. 
The method is grounded on the fact that 100 parts of 
water will dissolve 36 parts of pure salt. If we suc- 
ceed, therefore, in finding how much salt comes to solu- 
tion in a known fluid, whose entire water will dissolve 
the same, the water contents of this fluid may be calcu- 
lated from it. Fuchs has constructed a halimeter for 
this determination of salt (see Fig. 13), which consists 
of a graduated spindle, open at the upper, thickejr 
end, and closed at the lower, thinner end, whose di- 
visions give in grains of the old Prussian apothe- 
caries 1 weight the quantities of the residue of salt re- 
maining undissolved in a liquid. Applied to milk the 
process is as follows : 



1 Die Milch, von Benno Martinez, 



61 




Fig. 13. Reichelt-Haumetbic Test. 



One thousand grains (= 62.5 grm.) of the milk to 
be tested are mixed in a flask with 324 grains (= 20. 
25 grm.) of salt, and 240 grains (=15 grm.) of tinc- 
ture of litmus saturated with common salt, and re- 
peatedly shaken at 25° to 30° K., then poured off into 
the halimeter, so that none of the undissolved salt re- 
mains behind in the flask ; and after this has set- 
tled in the halimeter, and has been shaken close to- 
gether, its quantity is read off, the water contents of 
the milk are then calculated from the grains of dis- 
solved salt found. These — n, after the equation 
36 : 100 = n : x, or the same by multiplication of n. 
2.7778. The addition of the tincture of litmus is 
merely for the purpose of making the limit of the salt- 



62 



residue more distinctly recognizable, partly by the 
coloring, partly by the dilution of the milk. 1 

In one experiment the salt-residue amounted to four 
grains. One thousand grains of milk, therefore, dis- 
solved 320 grains of salt, corresponding to 888.89 gr. 
water, or 111.11 gr. dry substance. The determina- 
tion of the dry substance of the same milk by evapora- 
tion with quartz-addition, and drying at 100° to 
110° C, gave 11.033 per cent., consequently a differ- 
ence of 0.078 per cent. In an examination of cream 
the halimetric test gave 14.308 per cent, dry substance ; 
the evaporating test, 14.696 per cent, dry substance ; 
difference, 0.390 per cent. 

Another milk of 10 per cent, contents in dry sub- 
stance was diluted with two per cent, in weight of 
water. The halimetric examination of this diluted 
milk gave 9.722 per cent, dry substance, while from 
calculation there should be 9.804 per cent.; difference, 
0.082. 

Benno Martinez 2 says : " The method furnishes quite 
exact results, and is besides easily and rapidly per- 
formed. From its nature, however, it can be of use 
only where one has to do with notoriously adulte- 
rated milk, and here of but slight use, as it can give 
no information on the relation of the parts of the dry 
substance to one another." 

[method of vernois and becqtjerel. 

Vernois and Becquerel proposed to determine the 
milk-sugar in milk, and thus to judge of its quality. 
This was accomplished by means of a polarimeter, 
which consists, according to Yogel 3 of a hollow tube 

Reichelfc Wagner, Jahresbericht iiber die Fortschritte und Lusfcun- 
gen der chemise aen Technologie fur 1859, S. 443 ; aus Jahresber. iib. 
d. k. Landw. u. G-ewerbesclrale zu Ausbach, 1858-59, u. 1859-60, Aus- 
bach, 1859 u. 1860. 
, ^ a Loc. cit. 
^, 3 Eine neue Milcbprobe, Erlangen, 1862, p. 11. j 



63 



0.3 metre long and 0.02 metre in diameter, both ends 
of which are provided with Nicol prisms. The rays of 
light fall in through the front prism or the polarizer ; 
the second or analyzer is brought before the eye. If 
the entering light is examined in the empty tube, and 
with such a position of the prisms that their principal 
surfaces are parallel with one another, the rays of light 
are seen in their highest intensity. If the analyzer be 
turned about the axis of the tube and the parallelism 
of the prisms thus removed, every trace of light ceases, 
as soon as the principal surfaces stand at right angles 
with each other. If a fluid is now introduced into 
the tube which has an influence on the plane of polar- 
ization, the analyzer must be turned in a different 
way, sometimes more and sometimes less, in order to 
bring back darkness again. 

METHOD PROPOSED BY POGGIALE. 1 

Poggiale proposed to ascertain the sugar in milk by 
means of the Soleil saccharometer, and thus to judge 
of its richness. He proceeded as follows : 

The milk was coagulated with acetic acid at 40 to 
50° C, a few drops of acetate of lead added to the 
serum, and again filtered, the filtrate poured into a 
tube 22 centimetres long and after closing up put into 
the apparatus. In this apparatus 201.9 grm. of sugar 
of milk dissolved in 1,000 cub. cent. (1 litre) of water 
indicate 100 degrees. If we denote by g the number 
of the degrees found in the testing of whey as to the 
sugar of milk, the sugar of milk contents in a litre 
are calculated according to the formula 100: 201.9= 
g : x. The following table is founded on this for- 
mula: 



1 Dosage du sucre de lait au moyen du sacharimetre de M. Soleil et 
determination de la rechesse du lait Comptes Rendus, xxviii., 1849, 
p. 584. 



64 



Degree 


Gramme 


Degree 


Gramme 


found. 


Milk-Sugar. 


found. 


Milk-Sugar. 


18 


36.84 


26 


52.49 


19 


38.36 


27 


54.51 


20 


40.38 


28 


56.53 


21 


42.39 


29 


58.55 


22 


44.41 


30 


60.57 


23 


46.43 


31 


62.58 


24 


48.45 


32 


64.60 


25 


50.57 







According to Poggiale the serum of pure milk 
should show 28°, corresponding to 56.5 gr. of sugar of 
milk in the litre of serum and 52.7 gr. in the litre of 
milk. 



TEST OF MILK BY MEANS OF CENTRIFUGAL FORCE. 

C. J. Fuchs, Professor of the Veterinary School in 
Karlsruhe, proposed (1859) the employment of a cen- 
trifugal apparatus. He states his process as follows : 
Common cylindrical test-glasses divided into centi- 
metres are enclosed in paper, placed in correspond- 
ingly formed tin boxes, and the latter are so fastened 
on a centrifugal disk accelerated ten-fold by carrying 
over, that they can assume a horizontal position in 
swinging around. Fresh milk from a dealer showed 
-£s of cream on the average after 300 turns or 3,000 
rotations, and just as much was obtained from the 
same milk, when left in the same glass it had stood 
from twelve to twenty-four hours. Also, milk which 
had been diluted with a definite quantity of water 
showed a diminution of the cream corresponding to 
this quantity of water. If the milk was fatter than 
usual, a correspondingly greater quantity of cream 
was found by the centrifugal machine, as well as by 
spontaneous separation, namely, from 6 to 10 per cent. 
All the butter-globules were not, however, brought to 
the surface of the milk by the centrifugal machine. 



65 



The turning of the glass cylinders, instead of in the 
centrifugal machine, fastened on a rod seven to eight 
feet long with a wire four or five feet long on a loose 
ring, did not give the desired success, probably, as 
Fuchs says, because the rotations could not be effected 
quickly enough, and the greater length of the arch of 
rotation could not make up for the more rapid revo- 
lution of the centrifugal machine; besides, it was hard 
work, and much practice was necessary for an easy 
motion. Fuchs constructed therefore a particular 
small centrifugal machine especially for the test of 
milk. On a stand a disk lying horizontally 60 cm. 
in diameter is fastened and set in motion by a winch. 
Opposite to this disk stands a second, 6 cm. in diam- 
eter, which is moved ten times more rapidly by a cord 
running over both from the first disk. Through the 
smaller disk goes an angle projecting over it about 
one foot, on which there is an iron cross horizontally 
at the top, and on its ends the tin boxes for contain- 
ing the milk vessels are hung by means of wires, so 
long that in turning round they describe a circle of 
two to three feet in diameter. This machine furnished 
the same result as the previously employed centrifugal 
apparatus ; but after frequently repeated experiments, 
as it was made mostly of wood, its motion was ir- 
regularly distributed. 1 

REMARKS. 

I must again call to mind the fact, that before we 
can adopt the method for determining the quality of 
milk, a standard must be recognized which will repre- 
sent the poorest pure healthy milk. In the case of the 
specific gravity of milk, this standard has been accu- 
rately determined, and is recognized by those who 
have the most right to speak on this subject, but un- 
fortunately, as yet, for the other methods I have 

1 Die Milch, von Benno Martinez, p. 176. 



66 



described, there is no recognized standard, and al- 
though many of them may be of great value until the 
true standard is obtained, they remain perfectly useless 
for the purposes they are intended for. 

DETECTION OF CHALK. 

When chalk is added to milk, it readily subsides if 
the sample is allowed to remain at rest for some time, 
particularly if a little water be added. So that, if in 
a tube a sample of milk is put, containing this adul- 
terant, and allowed to remain at rest, we will have 
two layers formed, one on top and the other at the 
bottom ; if to this bottom layer (which I suppose the 
milkman means us to consider an extra layer of cream), 
hydrochloric acid is added, effervescence takes place, 
and the chalk is dissolved to a solution, in which the 
characteristic properties of a lime-salt can be recog- 
nized. 

STARCH, FLOUR, DECOCTION OF BARLEY, RICE, EMUL- 
SION OF ALMONDS AND HEMPSEED. 

By boiling the sample of milk suspected to contain 
one or more of these adulterants, and adding tincture 
of iodine, the amylaceous substances, if present, will 
produce a blue coloration in the fluid. 

For the detection of starch in milk and cream the 
microscope is much to be preferred. A little of the 
milk is spread out to a very thin stratum and then 
examined under the microscope. The examination is 
aided by tincture of iodine. 

It is considered better to coagulate the milk with 
acetic acid, and search the feculain the coagulated 
casein. 

DEXTRINE. 

Dextrine may be detected by adding to the sus- 
pected fluid iodine water, where a more or less vio- 



67 



let-blue coloration appears. It is better to act on the 
milk coagulated by acetic acid. 

The dextrine can also be inverted by means of sul- 
phuric acid, and tested by means of the polarimeter. 
In this way Adrian has established for 



Pure Milk. Density. 


Rotation to the Eight. 


0.10 of solution of dextrine. 1.0305 


22. 


0.20 of water, 0.10 " 1.032 


32.25 


0.15 " 0.10 " 1.0305 


31.5 



Laury found that if iodine be added to pure serum, 
it will be colored yellow, but, if the serum is mixed 
with 0.39 of dextrine, it will be colored dark blue; 
with 0.10, it is violet-blue, with 0.01, it is orange. 

CANE-SUGAR. 

To detect the presence of cane-sugar, the milk 
should be coagulated, and the serum evaporated at a 
gentle heat ; if the residue is darker than usual, the 
presence of sugar may be suspected (as brown sugar is 
generally used). The residue may then be dissolved 
in distilled water, and a little yeast added, when the 
fluid should be exposed for some hours at a tempera- 
ture of between 70° and 80° F. If fermentation en- 
sues, " it is a sure sign of the presence of sugar, for 
milk sugar cannot ferment, at least in so short a time, 
as the fermentation is never brisk. But the smallest 
proportion of sugar, either grape or cane-sugar, very 
speedily gives rise to a tumultuous fermentation." — 
Normandy. 

The carbonic acid may be collected, and the sugar 
calculated either from it or from the alcohol formed. 

GUM ARABIC AND GUM TRAGACANTH. 

To detect gum araoic, the serum of milk must be 
evaporated, and the residue boiled and digested with 
alcohol, which will take up the sugar and leave the 
gum. Or, the alcohol may be poured into the whey, 
when the gum will be precipitated in a white opaque 



OS 



flock, which, when collected and dried, may be identi- 
fied by its appearance. To detect gum tragacanth, it 
has been " recommended to boil the milk, and leave it 
at rest for some hours, when a gelatinous translucid 
deposit will be formed, which, being washed with a 
small quantity of water and tested by a few drops of 
solution of iodine, produces a blue color because gum 
tragacanth contains starch. The starch is plentiful 
and is in the form of starch corpuscles; these are 
rather small, but vary much in size ; many are irreg- 
ular, some are rounded, others are somewhat polyg- 
onal, while a few are muller-shaped ; in the more 
perfect grains a rounded hilum is distinctly visible." 

[salt. 

To detect the addition of salt, the most accurate 
method is to determine the percentage of chlorine. 
The ash may also be tasted, which, if strongly saline, 
indicates the addition of salt. 

DETECTION OP CARBONATE AND BICARBONATE OP 
SODA. 

When these salts are used the milk possesses a strong 
alkaline reaction, furnishes a serum having a sharp, 
bitter taste, and leaves a residue of the salt upon evap- 
oration, which can be recognized by the usual tests, 

DETECTION OP ANNATTO. 

If the milk, when evaporated to a small volume, 
possesses a reddish or orange-red color, annatto may 
be suspected. If by the addition of an acid the color 
is rendered purplish, or by an alkali rendered brighter 
red, its presence is certain. The color may be ex- 
tracted from the soft residue by means of alcohol, and 
tested with an acid and alkali as above. The color of 
the serum may also be observed. 



69 



DETECTION OF TURMERIC. 

In some cases turmeric cells may be detected by the 
microscope. It is best to examine the fluid in the 
same manner as for annatto. The turmeric is rendered 
deep brown by alkalies, and may be thus distin- 
guished. 

DETECTION OF GELATIN. 

Gelatin and isinglass have been detected in milk 
by Morin, at Rouen. It may be detected by treating 
the serum with tannin, when it will be precipitated. 
To the precipitate is then to be applied the usual 
tects. 

detection of cerebral matter. 

Wheu a sample of milk containing cerebral matter 
is examined under the microscope, portions of nerve 
tubules are readily discovered. Professor Queckett 
obtained a sample of milk adulterated by this sub- 
stance. 



286 78 54? 



